Fix AI-reported bugs against current main type rules

[mattcasters]

Verified against current main / 2.20 type rules, not 2.19 getFieldDefinition. That is the answer to the review notes on #8220 / #8221.

Already handled by #8214 (Database perspective)

These are not in this PR. Comments are on the issues; they should close when #8214 merges:

• [Bug]: The query timeout is not applied to DDL/DML statements #8224 query timeout on DDL/DML
• [Bug]: Database cancel-watcher threads never terminate in Hop Web — two of them are non-daemon #8228 cancel-watcher leak in Hop Web
• [Bug]: SQL editor fetches the whole result set — its 1000-row limit is applied client-side only #8229 SQL editor 1000-row cap is client-side only

#8217 was already closed (UNIQUEIDENTIFIER on both SQL Server dialects).

This PR

Issue	Change
#8216	Hop Number length is JDBC precision (total digits). numericLength() stays integer digits for dialect rule conditions. PostgreSQL writes NUMERIC(length, scale) so it round-trips. Does not merge #8242 as-is (that inverts numericLength() and would inflate Postgres precision).
#8218	Timestamp parse mask reads HOP_DEFAULT_TIMESTAMP_FORMAT
#8219	Stream Lookup Timestamp default no longer throws ConversionNotImplemented
#8220	SQL Server DATE / TIME / DATETIME2 via type rules; new Date fields stay DATETIME
#8221	SQL Server NVARCHAR/NCHAR preserved; TEXT replaced with VARCHAR(MAX)
#8222	Parameter metadata goes through StandardJdbcTypeMapper (NVARCHAR, NUMERIC(p,s))
#8223	Ordinary JDBC no longer calls the data-service getColumns() path
#8225	Empty leftover metadata folders are not listed under Unknown
#8226	catalog.schema is split even when supportsCatalogs() is false
#8227	ProgressMonitorDialog disposes when the runnable returns (Get fields no longer hangs)
#8230	Dead View-menu terminal constants and unused USE_ADVANCED_TERMINAL key removed

Tests

Focused modules run under tools/with-isolated-display.sh: core, ui, mssql, mssqlnative, postgresql (+ redshift/greenplum/cockroach), mysql, oracle, streamlookup.

Fixes #8216 #8218 #8219 #8220 #8221 #8222 #8223 #8225 #8226 #8227 #8230

[fskorgen]

Thanks for taking these on!

We run 2.19 in production and have local patches for a few of them, so we are not
blocked. But #8216 is the one that hurts: the shortened DECIMAL length breaks our
job runs. That fix looks self-contained in StandardJdbcTypeMapper, which is in 2.19
too, unlike the SQL Server ones that need the 2.20 type rules.

We have patched #8220/#8221 ourselves, but anyone else on 2.19 with SQL Server will
get wrong DDL for Unicode columns.

Is a 2.19 patch release planned, and could #8216 go into the 2.19 branch?

[mattcasters]

Thanks for filing the issues @fskorgen. If you're not blocked my idea is that it's best for give this PR some mileage until the 2.20.0 release in October. 2.19.0 should have a compatibility flag for the DDL issues as well so not so blocking for others either I think.
The flag is gone in main (2.20.0) since the backend got reworked with even more flexibility. That's what the comments from @hansva were about.
If you find the time, do try out this PR and let us know if there's anything missing for your deployment.