DuckDB, MySQL, Spark, Databricks, Hive, ClickHouse: Accept string literal aliases only where each engine does

[LucaCappelletti94]

Follow-up to #2668, which this PR is stacked on.

Engines differ on single-quoted string aliases. SQLite 3.51.1 accepts SELECT 1 AS 'x', SELECT 1 'x', FROM t AS 'y' and FROM t 'y'. DuckDB 1.4.4 accepts only the two forms with AS. MySQL accepts a string as a column alias but not as a table alias (select_alias against opt_table_alias in https://github.com/mysql/mysql-server/blob/trunk/sql/sql_yacc.yy). Spark (namedExpression and tableAlias in https://github.com/apache/spark/blob/master/sql/api/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBaseParser.g4), Hive (selectItem and tableAlias) and ClickHouse (ParserAlias only takes identifiers, https://clickhouse.com/docs/reference/syntax#identifiers) accept none of them. Every one of these dialects accepted all four forms.

supports_string_literal_alias is replaced by supports_string_literal_column_alias and supports_string_literal_table_alias, each told whether the alias follows AS. Both default to true, so dialects whose engines were not checked are unchanged. A per-engine test pins all four forms for PostgreSQL, SQLite, DuckDB, MySQL, Spark, Databricks, Hive and ClickHouse, and a capability-driven test checks every dialect against the exact errors.

I used Opus in support of this PR to try and include all relevant dialects, I checked the various documentations it found and they seem correct to me.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.15385% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.32%. Comparing base (d32825d) to head (560faf2).

Files with missing lines	Patch %	Lines
src/parser/mod.rs	81.81%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2669      +/-   ##
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+ Coverage   81.29%   81.32%   +0.02%     
==========================================
  Files          42       42              
  Lines       33950    33994      +44     
  Branches    33950    33994      +44     
==========================================
+ Hits        27601    27645      +44     
  Misses       2785     2785              
  Partials     3564     3564              

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