feat(macos): add RCTUITableView/RCTUIButton compatibility primitives and adopt them in RedBox

[Saadnajmi]

Summary

Adds three narrow RCTUIKit compatibility primitives and adopts them in RedBox, which collapses most of RedBox's platform forking.

• RCTUITableView / RCTUITableViewCell — @compatibility_alias to UITableView/UITableViewCell on iOS and visionOS; on macOS an NSScrollView subclass wrapping a private NSTableView, with narrow data-source/delegate protocols and an exact NSIndexPath row/section bridge.
• RCTUILabel — implements the text getter and the numberOfLines/textAlignment pairs that were already declared in the header but never backed.
• RCTUIButton / RCTUIAction — narrow NSButton subclass plus a small title proxy and a block-based action holder, replacing RedBox's objc_setAssociatedObject category.

RedBox drops from 1125 to 912 lines. Platform-forked lines fall from 441 to 174 (macOS-only 248 → 96, iOS-only 193 → 78) and conditional blocks by 10.

macOS design notes

• The macOS table flattens sections and headers into a single backing row list, and uses NSTableViewStyleInset explicitly.
• Row heights use AppKit's native usesAutomaticRowHeights. Fixed heights come from an explicit height constraint on the cell; tableView:heightOfRow: supplies the estimate. Automatic heights come from AutoLayout, with preferredMaxLayoutWidth maintained as the cell resizes so text reflows on window resize.
• Header views are created lazily, cached per reload generation, and pointer-stable within a generation. Sections with zero header height get no slot at all.
• Cells go through real makeViewWithIdentifier: reuse, so prepareForReuse is driven by AppKit rather than called manually.

RedBox behavior changes

Visuals are intended to be unchanged. The macOS RedBox keeps its 16pt inset and 8pt continuous-radius message card, and the buttons keep their existing borderless momentary-push appearance, attributed titles, and key equivalents (⎋ / ⌘R / ⌥⌘C).

Bugs fixed along the way, all of which were coupled to the migration:

• Stack rows are now recycled instead of a new cell being built for every row.
• Reused rows have their line limits and identifiers reset unconditionally, instead of leaking a 3-line limit onto later rows.
• The message cell's accessibility identifier was "red box-error" and is now redbox-error, matching iOS.
• A nil error message is now mapped through the section count rather than shifting every stack row by one.
• redBoxButton: set its accessibility identifier to the literal string @"accessibilityIdentifier" instead of the parameter.
• The macOS message text is selectable again.

Adds a unit test target file

RCTUITableViewTests.m covers sections and empty sections, reloads, real reuse (first dequeue nil, bounded allocation, no double attachment, prepareForReuse exactly once), selection/deselection and header non-selection, mixed automatic/fixed heights reflowing with content width, lazy pointer-stable headers, accessibility containment, scrolling, and label/button/action forwarding. Tests run against a real NSApplication with an offscreen NSWindow and forced layout, and are registered in both the iOS and macOS unit-test targets.

Validation status — draft; a reported visual regression has been addressed but not re-verified

A macOS capture of the previous revision showed the RedBox message card losing its rounded
corners and its text insets, and stack frame rows clipped at the top. This revision addresses
all three:

• The red background and the 8pt continuous corner radius are applied to the cell's own layer
  again, matching the code this PR replaces. No competing background is drawn over the corners.
• Subtitle-style cells now carry a 5pt top inset and a 5pt bottom inset, which the previous
  revision had dropped to zero.
• RCTUITableViewCell sets rowSizeStyle = NSTableViewRowSizeStyleCustom, so NSTableCellView
  does not apply its own standard metrics to the textField outlet.
• Header views now reuse a single identified height constraint instead of gaining a new one on
  every reload.

Two new tests cover this: one asserts >=5pt label containment for both cell styles and the
message card's layer radius against a real table after a real reload and layout pass; the other
asserts that a header view reused across reloads keeps exactly one active height constraint whose
constant is updated in place.

These fixes have NOT been visually re-verified, and the tests have never been executed.
Do not merge until all of the following pass:

• Execute RCTUITableViewTests on both unit-test targets — never run yet
• RNTester macOS native project build (pod install + xcodebuild)
• RNTester iOS native project build
• visionOS build
• Capture the RedBox sheet on main and on this branch at an identical window size and
  compare corner radius, text insets, glyph tops, 16pt row inset, and the footer

Known risk: NSTableView assigns its effectiveRowSizeStyle onto each cell view, so the
cell-side rowSizeStyle may need to be set on the table as well. The new layout test asserts
the resulting value and will surface this as soon as it runs.

Known follow-ups

• The RedBox message-height estimate measures against the scroll view's content width minus 30, which does not account for the inset style's row padding. Worth confirming during the GUI pass that long messages are not clipped.
• RCTUITableViewAutomaticDimension and the header APIs have no consumer in this PR.