[WIP][SPARK-49085][SQL] Remove special casing for Protobuf functions in Connect

[itholic]

What changes were proposed in this pull request?

This PR proposes to remove special casing for Protobuf functions in Connect

This PR try resolving the follow tasks described from ticket:

• Remove the special casing from the connect planner
• Register the protobuf functions under system.internal using session extensions
• Add the needed constructors to the protobuf expressions
• Update protobuf functions and make them use unresolved function path

Why are the changes needed?

For unifying SQL Scala interface between Connect and Classic.

Does this PR introduce any user-facing change?

No API changes from users' perspective

How was this patch tested?

The existing CI should pass

Was this patch authored or co-authored using generative AI tooling?

No