refactor: Add DSL validation for cloud eligible check

[ritchie46]

@stinodego @c-peters here is the skeleton for the DSL cloud validation

[codecov]

Codecov Report

Attention: Patch coverage is 68.37607% with 37 lines in your changes missing coverage. Please review.

Project coverage is 80.72%. Comparing base (c6e1d9e) to head (a297d25).
Report is 3 commits behind head on main.

Files	Patch %	Lines
crates/polars-plan/src/client/dsl.rs	52.30%	31 Missing ⚠️
crates/polars-plan/src/client/mod.rs	82.85%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17287      +/-   ##
==========================================
+ Coverage   80.70%   80.72%   +0.01%     
==========================================
  Files        1485     1489       +4     
  Lines      195518   195628     +110     
  Branches     2782     2782              
==========================================
+ Hits       157798   157924     +126     
+ Misses      37208    37192      -16     
  Partials      512      512              

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[stinodego]

@ritchie46 I covered the cases I could think of - any other cases we should reject?

I will rewrite this to a "prepare plan" util as discussed later - when I add the sink capability.

[ritchie46]

Looks good. We miss a few expressions.