[fix] SQL parsing of table names

[john-bodley]

CATEGORY

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• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

Presto supports using the optional cluster when specifying the table name, i.e., [[cluster.]schema].table however the currently SQL parse logic only returns at most the first two components, i.e., cluster.schema if a cluster was defined.

This PR extends the logic to support the [[cluster.]schema].table construct as well as:

• Ensures the table construct is valid in terms of length and structure.
• Ensures that the quotes are removed from each token. Previously this was only the case when only the table was specified which were removed via get_real_name().
• The get_real_name() logic wasn't overly apparent though it's used when a table alias is present. I felt this logic wasn't overly clear and in the case of a TokenList representing schema.table AS foo the get_real_name() only returns table (though this wasn't invoked because there was the . token). From a table construct validity perspective it seems more prudent to strip the alias and then extract the full table name if valid.

TEST PLAN

CI.

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

to: @graceguo-supercat @michellethomas @mistercrunch

[codecov-io]

Codecov Report

Merging #7490 into master will increase coverage by 0.01%.
The diff coverage is 89.47%.

@@            Coverage Diff             @@
##           master    #7490      +/-   ##
==========================================
+ Coverage   65.42%   65.43%   +0.01%     
==========================================
  Files         435      435              
  Lines       21323    21330       +7     
  Branches     2347     2347              
==========================================
+ Hits        13950    13957       +7     
  Misses       7257     7257              
  Partials      116      116

Impacted Files	Coverage Δ
superset/sql_parse.py	99.2% <100%> (+0.05%)	⬆️
superset/security.py	76.08% <60%> (-0.11%)	⬇️

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