MONGOCRYPT-870 drop prefixPreview and suffixPreview

[kevinAlbs]

Summary

This PR applies renames for query types and algorithms related to QE string features.

• Setting the query type prefixPreview and suffixPreview is now an error.
• suffix and prefix require use of the string algorithm (formerly textPreview).

Details

The textPreview algorithm is still used for substringPreview. But textPreview may be dropped entirely if WRITING-37758 is approved. This is tracked in MONGOCRYPT-931.

Choosing string (rather than text) was motivated by a request to rename public driver APIs from "text" to "string": DRIVERS-3531

[blink1073]

I would have expected the python test that uses suffixPreview to have failed. I need to double-check that we're using the as-build version of libmongocrypt in our Evergreen tests.

[blink1073]

I would have expected the python test that uses suffixPreview to have failed. I need to double-check that we're using the as-build version of libmongocrypt in our Evergreen tests.

Ah, I missed that you had update the python tests.

[blink1073]

LGTM!

[kevinAlbs]

Drafting spec changes motivated an additional change: f1df06e drops "textPreview" entirely. "substringPreview" still signals the feature is experimental, and avoids continued use of the term "text".