Allow "." (dot) in identifier names in BasicPostgresSecurityValidator

[suddendust]

Description

Currently, BasicPostgresSecurityValidator does not allow . (dots) in identifier names. Therefore, query containing columns with names like a.b are getting rejected. We should allow for dots of type a.b as such column names are pretty common use-case (note: We're still rejecting col names starting with a ., ending with a . and containing two consecutive dots). This PR also refactors the code slightly by removing unnecessary comments and removing snake case from test method names.

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.10%. Comparing base (5c2ddf5) to head (07d62b5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #245   +/-   ##
=========================================
  Coverage     80.10%   80.10%           
  Complexity     1134     1134           
=========================================
  Files           215      215           
  Lines          5488     5488           
  Branches        482      482           
=========================================
  Hits           4396     4396           
  Misses          764      764           
  Partials        328      328           

Flag	Coverage Δ
integration	80.10% <ø> (ø)
unit	57.34% <ø> (ø)

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