feat: add literal parser

[olavloite]

[Work in progress] Add a literal parser to accept more values in execute statements.

[codecov]

Codecov Report

Merging #546 (2738441) into postgresql-dialect (b64cc7c) will decrease coverage by 0.56%.
The diff coverage is 80.06%.

@@                   Coverage Diff                    @@
##             postgresql-dialect     #546      +/-   ##
========================================================
- Coverage                 88.39%   87.82%   -0.57%     
- Complexity                 2063     2115      +52     
========================================================
  Files                       122      123       +1     
  Lines                      6771     6980     +209     
  Branches                    949     1014      +65     
========================================================
+ Hits                       5985     6130     +145     
- Misses                      558      599      +41     
- Partials                    228      251      +23     

Flag	Coverage Δ
all_tests	87.82% <80.06%> (-0.57%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...loud/spanner/pgadapter/utils/BinaryCopyParser.java	93.39% <ø> (ø)
...oud/spanner/pgadapter/parsers/TimestampParser.java	85.41% <71.42%> (-6.37%)	⬇️
...ud/spanner/pgadapter/statements/LiteralParser.java	78.73% <78.73%> (ø)
...oud/spanner/pgadapter/statements/SimpleParser.java	91.84% <80.00%> (-0.37%)	⬇️
...cloud/spanner/pgadapter/parsers/IntegerParser.java	76.92% <100.00%> (+0.92%)	⬆️
...le/cloud/spanner/pgadapter/parsers/LongParser.java	83.78% <100.00%> (+0.45%)	⬆️
...e/cloud/spanner/pgadapter/parsers/ShortParser.java	65.21% <100.00%> (+1.58%)	⬆️
.../cloud/spanner/pgadapter/session/CopySettings.java	96.61% <100.00%> (+0.05%)	⬆️
...spanner/pgadapter/statements/ExecuteStatement.java	85.50% <100.00%> (-6.02%)	⬇️
...spanner/pgadapter/statements/PrepareStatement.java	86.27% <100.00%> (-6.73%)	⬇️
... and 6 more

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