refactor(proto): migrate window serde

[Phoenix500526]

Which issue does this PR close?

• Closes Proto: migrate WindowAggExec + BoundedWindowAggExec #23513.

Rationale for this change

Window plans still relied on centralized protobuf dispatch, keeping serialization separate from the execution plans that own their state. Both window executors share one protobuf variant. Decoding must inspect input_order_mode before selecting the concrete plan.

Add plan-local encoders for both executors and a decoder for the shared node. Keep the legacy helpers as deprecated delegates while preserving window frames and UDF payloads on the existing wire format.

What changes are included in this PR?

Are these changes tested?

Yes

Are there any user-facing changes?

[github-actions]

Thank you for opening this pull request!

Reviewer note: cargo-semver-checks reported the current version number is not SemVer-compatible with the changes in this pull request (compared against the base branch).

Details

     Cloning apache/main
    Building datafusion-physical-plan v54.1.0 (current)
       Built [  36.481s] (current)
     Parsing datafusion-physical-plan v54.1.0 (current)
      Parsed [   0.148s] (current)
    Building datafusion-physical-plan v54.1.0 (baseline)
       Built [  35.659s] (baseline)
     Parsing datafusion-physical-plan v54.1.0 (baseline)
      Parsed [   0.148s] (baseline)
    Checking datafusion-physical-plan v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.904s] 223 checks: 223 pass, 30 skip
     Summary no semver update required
    Finished [  75.062s] datafusion-physical-plan
    Building datafusion-proto v54.1.0 (current)
       Built [  58.934s] (current)
     Parsing datafusion-proto v54.1.0 (current)
      Parsed [   0.020s] (current)
    Building datafusion-proto v54.1.0 (baseline)
       Built [  59.878s] (baseline)
     Parsing datafusion-proto v54.1.0 (baseline)
      Parsed [   0.020s] (baseline)
    Checking datafusion-proto v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.347s] 223 checks: 222 pass, 1 fail, 0 warn, 30 skip

--- failure trait_method_marked_deprecated: trait method #[deprecated] added ---

Description:
A trait method is now #[deprecated]. Downstream crates will get a compiler warning when using this method.
        ref: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.49.0/src/lints/trait_method_marked_deprecated.ron

Failed in:
  method try_into_window_physical_plan in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:721
  method try_from_window_agg_exec in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:721
  method try_from_bounded_window_agg_exec in trait datafusion_proto::physical_plan::PhysicalPlanNodeExt in /home/runner/work/datafusion/datafusion/datafusion/proto/src/physical_plan/mod.rs:721

     Summary semver requires new minor version: 0 major and 1 minor checks failed
    Finished [ 120.383s] datafusion-proto

[codecov-commenter]

Codecov Report

❌ Patch coverage is 73.22581% with 83 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.66%. Comparing base (9a50c67) to head (b398e8c).
⚠️ Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
...usion/physical-plan/src/windows/window_agg_exec.rs	77.73%	23 Missing and 34 partials ⚠️
datafusion/proto/src/physical_plan/mod.rs	4.76%	20 Missing ⚠️
...ysical-plan/src/windows/bounded_window_agg_exec.rs	81.81%	3 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #23780      +/-   ##
==========================================
- Coverage   80.69%   80.66%   -0.03%     
==========================================
  Files        1089     1089              
  Lines      368424   368970     +546     
  Branches   368424   368970     +546     
==========================================
+ Hits       297307   297639     +332     
- Misses      53406    53572     +166     
- Partials    17711    17759      +48     

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