fix: Unable to parse escaped tables

[michael-s-molina]

SUMMARY

#26476 introduced a SQLGLOT_DIALECTS mapping to be used when parsing SQL queries with SQLGlot. For companies that have custom database engines, with a name not present in the mapping, the default SQLGlot dialect would be used and could generate problems such as #30551. This PR adds a new configuration to allow extending registered SQLGlot dialects.

Fixes #30551

TESTING INSTRUCTIONS

Check the original issue for instructions.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 83.92%. Comparing base (76d897e) to head (81bcbf5).
Report is 842 commits behind head on master.

Files with missing lines	Patch %	Lines
superset/config.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #30560       +/-   ##
===========================================
+ Coverage   60.48%   83.92%   +23.43%     
===========================================
  Files        1931      533     -1398     
  Lines       76236    38544    -37692     
  Branches     8568        0     -8568     
===========================================
- Hits        46114    32349    -13765     
+ Misses      28017     6195    -21822     
+ Partials     2105        0     -2105     

Flag	Coverage Δ
hive	49.00% <85.71%> (-0.16%)	⬇️
javascript	?
mysql	76.79% <85.71%> (?)
postgres	76.89% <85.71%> (?)
presto	53.49% <85.71%> (-0.31%)	⬇️
python	83.92% <85.71%> (+20.43%)	⬆️
sqlite	76.34% <85.71%> (?)
unit	60.72% <85.71%> (+3.09%)	⬆️

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[betodealmeida]

Awesome!