Translate string.TrimStart/TrimEnd with a char parameter instead of d…

[ilkertskn]

…ropping it on SQL Server

On SQL Server 2022+ (compatibility level 160), TranslateTrimStartEnd accepts any single argument, but ProcessTrimStartEnd only handled SqlConstantExpression. A captured variable or parameter (var c = 'S'; ... x.TrimStart(c)) therefore fell through and the call was translated to the one-argument LTRIM(x), silently trimming whitespace instead of the requested character and returning wrong rows.

A non-constant char argument is now passed to LTRIM/RTRIM as a parameter with the char type mapping, and a non-constant char[] argument makes the translation fail (as SQLite already does) instead of being dropped.

Adds parameterized TrimStart/TrimEnd tests to StringTranslationsTestBase with SQL Server, SQLite and Cosmos overrides.

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