feat(cubesql): Support trivial casts in member pushdown

[mcheshkov]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made (if issue reference is not provided)

This should allow pushing down expressions like CAST(dimension AS TEXT) AS alias into CubeScan as regular dimensions.
This should allow __cubeJoinField joins to see more CubeScans

Supporting changes:

Remove unused rule for member pushdown from AllMembers
All matching happening with CubeScanMembers on top of actual members node, and this rule does not expect that
member_name_to_expr part of analysis can extract members from CubeScanMembers(AllMembers), so there's no reason to keep this rule

Add explicit type in var! macro, to avoid type confusion.

[codecov]

Codecov Report

Attention: Patch coverage is 98.38710% with 3 lines in your changes missing coverage. Please review.

Project coverage is 76.65%. Comparing base (e7901a7) to head (a7c10cd).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...besql/cubesql/src/compile/rewrite/rules/members.rs	97.43%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #9480       +/-   ##
===========================================
+ Coverage   48.03%   76.65%   +28.61%     
===========================================
  Files         171      400      +229     
  Lines       21449   105018    +83569     
  Branches     3723     3724        +1     
===========================================
+ Hits        10303    80500    +70197     
- Misses      10714    24086    +13372     
  Partials      432      432               

Flag	Coverage Δ
cube-backend	48.02% <ø> (-0.02%)	⬇️
cubesql	84.00% <98.38%> (?)

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