Add support for OFFSET

[lziq]

Issue #422

Changes Details:

1. Added OFFSET in the PIG domain.

[alancai98]

Addition to the PIG domain looks good.

I have a few minor suggestions for the PR:

• Since this is the first task of issue Add support for OFFSET  #422, this PR shouldn't be linked to close that issue. I would link the issue in the final task's PR
• I'd rename the PR title to reflect this is adding OFFSET to the PIG domain
• Try keeping the PR's commit history clearer by creating a new branch off the target branch for each new PR. Doing this will prevent non-relevant commits from appearing in the PR, which may confuse the reviewer.

[alancai98]

Order needs changed for LIMIT and OFFSET in the visitor transform tasks

[codecov-commenter]

Codecov Report

Merging #451 (96f781f) into main (28701e2) will increase coverage by 0.01%.
The diff coverage is 86.95%.

@@             Coverage Diff              @@
##               main     #451      +/-   ##
============================================
+ Coverage     82.36%   82.37%   +0.01%     
- Complexity     1395     1399       +4     
============================================
  Files           171      171              
  Lines         10722    10741      +19     
  Branches       1766     1771       +5     
============================================
+ Hits           8831     8848      +17     
- Misses         1350     1351       +1     
- Partials        541      542       +1     

Flag	Coverage Δ
CLI	18.18% <ø> (ø)
EXAMPLES	74.85% <ø> (ø)
LANG	84.87% <86.95%> (+<0.01%)	⬆️
PTS	∅ <ø> (∅)
TEST_SCRIPT	79.68% <ø> (ø)

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

Impacted Files	Coverage Δ
lang/src/org/partiql/lang/ast/AstSerialization.kt	85.57% <33.33%> (-0.41%)	⬇️
lang/src/org/partiql/lang/syntax/SqlParser.kt	79.79% <80.00%> (+0.06%)	⬆️
...ng/src/org/partiql/lang/ast/ExprNodeToStatement.kt	93.79% <100.00%> (+0.02%)	⬆️
...ng/src/org/partiql/lang/ast/StatementToExprNode.kt	97.36% <100.00%> (+<0.01%)	⬆️
lang/src/org/partiql/lang/ast/ast.kt	89.15% <100.00%> (+0.02%)	⬆️
...src/org/partiql/lang/ast/passes/AstRewriterBase.kt	100.00% <100.00%> (ø)
lang/src/org/partiql/lang/ast/passes/AstWalker.kt	71.33% <100.00%> (+0.19%)	⬆️
...ng/src/org/partiql/lang/eval/EvaluatingCompiler.kt	84.22% <100.00%> (ø)
.../visitors/GroupByPathExpressionVisitorTransform.kt	82.89% <100.00%> (+0.46%)	⬆️
...partiql/lang/eval/visitors/VisitorTransformBase.kt	97.43% <100.00%> (+0.13%)	⬆️
... and 2 more

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[lziq]

Will finish all the 3 tasks from issue #422 in this branch, and afterwards merge this PR into main.

[alancai98]

Looks good for the PIG domain and VisitorTransform changes.

For the remaining two tasks, I'd create separate PRs targeting this branch, add-OFFSET. After those PRs are merged into add-OFFSET, this PR can be looked at again.