Support Parsing ALTER TRIGGER in PostgreSQL

[everly-gif]

Ref #17848
Sub-issue of #14015

Changes proposed in this pull request:

• Proofread ALTER TRIGGER grammar
• Support Parsing ALTER TRIGGER in PostgreSQL
• Adds tests

✅ Builds locally

[codecov-commenter]

Codecov Report

Merging #20611 (fa131e8) into master (6692919) will decrease coverage by 0.00%.
The diff coverage is 50.00%.

@@             Coverage Diff              @@
##             master   #20611      +/-   ##
============================================
- Coverage     61.06%   61.06%   -0.01%     
  Complexity     2414     2414              
============================================
  Files          3951     3952       +1     
  Lines         54878    54880       +2     
  Branches       9318     9318              
============================================
+ Hits          33509    33510       +1     
- Misses        18522    18523       +1     
  Partials       2847     2847              

Impacted Files	Coverage Δ
...ostgresql/ddl/PostgreSQLAlterTriggerStatement.java	0.00% <0.00%> (ø)
...atement/impl/PostgreSQLDDLStatementSQLVisitor.java	85.57% <100.00%> (+0.03%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more