refactor(proto): migrate SortExec and SortPreservingMergeExec serde

[buraksenn]

Which issue does this PR close?

• Closes Proto: migrate SortExec + SortPreservingMergeExec #23505.

Rationale for this change

Part of epic #23494. Moves SortExec and SortPreservingMergeExec protobuf serialization from central dispatch.

What changes are included in this PR?

Add protobuf serialization and deserialization to the physical plan implementations and deprecate the corresponding central proto methods. The wire format remains unchanged.

Are these changes tested?

Yes, existing round-trip tests cover these plans.

Are there any user-facing changes?

Existing methods are deprecated with no immediate API change.

[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 [  42.295s] (current)
     Parsing datafusion-physical-plan v54.1.0 (current)
      Parsed [   0.139s] (current)
    Building datafusion-physical-plan v54.1.0 (baseline)
       Built [  35.079s] (baseline)
     Parsing datafusion-physical-plan v54.1.0 (baseline)
      Parsed [   0.134s] (baseline)
    Checking datafusion-physical-plan v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.595s] 223 checks: 223 pass, 30 skip
     Summary no semver update required
    Finished [  79.827s] datafusion-physical-plan
    Building datafusion-proto v54.1.0 (current)
       Built [  57.121s] (current)
     Parsing datafusion-proto v54.1.0 (current)
      Parsed [   0.019s] (current)
    Building datafusion-proto v54.1.0 (baseline)
       Built [  57.274s] (baseline)
     Parsing datafusion-proto v54.1.0 (baseline)
      Parsed [   0.018s] (baseline)
    Checking datafusion-proto v54.1.0 -> v54.1.0 (no change; assume patch)
     Checked [   0.254s] 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_sort_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_into_sort_preserving_merge_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_sort_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_sort_preserving_merge_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 [ 115.842s] datafusion-proto