MSSQL: Support PROC as CREATE PROCEDURE abbreviation

[t8y2]

Adds support for the T-SQL PROC abbreviation in both CREATE PROC and CREATE OR ALTER PROC.

The parser gates the syntax through a dialect capability and normalizes the AST display to PROCEDURE. Tests also verify that CREATE PROC remains MSSQL-specific and that proc can still be used as an identifier.

Reference: https://learn.microsoft.com/en-us/sql/t-sql/statements/create-procedure-transact-sql

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.09%. Comparing base (91f7ce2) to head (a3801e7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2448   +/-   ##
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  Coverage   81.09%   81.09%           
=======================================
  Files          42       42           
  Lines       33677    33684    +7     
  Branches    33677    33684    +7     
=======================================
+ Hits        27309    27316    +7     
  Misses       2798     2798           
  Partials     3570     3570           

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[LucaCappelletti94]

LGTM!

@t8y2 do consider reviewing some of the other open PRs, we'd really appreciate it!

cc @alamb @iffyio