refactor: Rationalize SQL dialect and statement code, to simplify adding new dialects

[ferenc-csaky]

Key Changes

• Centralized dialect SQL translation discovery and dispatch.
• Made translation maps immutable and locale-safe.
• Consolidated relational-plan and SQL-string conversion into SqlConverters.
• Replaced duplicated dialect converter pairs with shared conversion logic.
• Added service-based lookup for dialect SQL converters.
• Updated JDBC statement factories to use the consolidated converter.

Snapshot Diffs

1. I turned back on escaping in Snowflake
2. Some postgres ocnverters were instantiated multiple times before, that causes the generated index diff

[codecov]

Codecov Report

❌ Patch coverage is 31.08108% with 51 lines in your changes missing coverage. Please review.
✅ Project coverage is 17.10%. Comparing base (98a02a8) to head (e589ac2).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...sqrl/calcite/dialect/SqlTranslationDispatcher.java	0.00%	17 Missing ⚠️
...atasqrl/calcite/convert/AbstractSqlConverters.java	7.14%	13 Missing ⚠️
...abase/relational/AbstractJdbcStatementFactory.java	0.00%	8 Missing ⚠️
...tasqrl/calcite/convert/SnowflakeSqlConverters.java	50.00%	2 Missing ⚠️
...tasqrl/calcite/dialect/BasePostgresSqlDialect.java	0.00%	2 Missing ⚠️
...database/relational/SnowflakeStatementFactory.java	0.00%	2 Missing ⚠️
.../java/com/datasqrl/calcite/SqrlConfigurations.java	0.00%	1 Missing ⚠️
...m/datasqrl/calcite/convert/FlinkSqlConverters.java	50.00%	1 Missing ⚠️
...com/datasqrl/calcite/dialect/DuckDbSqlDialect.java	83.33%	1 Missing ⚠️
...rl/calcite/dialect/ExtendedPostgresSqlDialect.java	87.50%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2235      +/-   ##
============================================
+ Coverage     16.91%   17.10%   +0.18%     
- Complexity     1040     1045       +5     
============================================
  Files           613      611       -2     
  Lines         17738    17693      -45     
  Branches       2155     2155              
============================================
+ Hits           3001     3026      +25     
+ Misses        14425    14355      -70     
  Partials        312      312              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[mbroecheler]

Looks good. I did not validate the snapshot changes.