Widens the two provider gates so an authored `{"provider":"Postgres"}` or
`{"provider":"Oracle"}` binds that provider's own dialect instead of failing
"not available in this build":
- `SqlDriverFactoryExtensions.CreateDialect` gains a Postgres and an Oracle
arm. There is deliberately no fallback arm — a default resolving to
SqlServerDialect would construct happily and then emit T-SQL at a Postgres
or Oracle server. The rejection message now names the three supported and
the two still-reserved providers.
- `SqlDriverBrowser.DefaultDialectSelector` widens identically, so a provider
the runtime constructs is also browsable; MySql/Odbc keep resolving to null
and the caller keeps reporting them as unavailable.
Tests: the existing rejected-provider controls flip from Postgres to MySql
(factory) and Odbc (browser) so the reserved half stays falsifiable, and the
new legs assert the bound dialect TYPE rather than mere construction —
"no throw" alone would pass against a SqlServer fallback.
Doc-comment sweep (contract addition, one line each): the "v1 constructs
SqlServer only" / "reserved for P2" claims in SqlProvider, SqlDriverConfigDto,
ISqlDialect.Provider and SqlServerDialect are now false and were corrected in
the same change.
Joseph Doherty
429ead837f