Enable custom dialects to support MATCH() AGAINST()

[joocer]

The logic for if a dialect supports MATCH() AGAINST() was coded into the parser to look for specific dialects rather than the dialects attesting they support the syntax. This meant that custom dialects were unable to take advantage of this feature.

The changes involve updating the Dialect trait and its implementations for the MySQL and Generic SQL dialects which support MATCH() AGAINST(), as well as modifying the parser to use the new method for determining support for this syntax.

Key changes include:

Dialect Trait Updates:

• src/dialect/mod.rs: Added a new method supports_match_against to the Dialect trait to indicate whether a dialect supports the MATCH() AGAINST() syntax.

Dialect Implementations:

• src/dialect/generic.rs: Implemented the supports_match_against method for the GenericDialect to return true.
• src/dialect/mysql.rs: Implemented the supports_match_against method for the MySqlDialect to return true.

Parser Update:

• src/parser/mod.rs: Updated the parser to use the supports_match_against method to check if the dialect supports the MATCH() AGAINST() syntax.

[iffyio]

Thanks @joocer!
cc @alamb