feat: remove argument and signature

[tianzhou]

Use parameter as the SOT

Fix #92

[Copilot]

Pull Request Overview

This PR removes the Arguments and Signature fields from database objects (Function, Procedure, Aggregate) and uses the Parameters array as the single source of truth for parameter information.

• Removes redundant Arguments and Signature fields from Function, Procedure, and Aggregate structs
• Adds GetArguments() method to Function for dynamic argument string generation
• Updates normalization and comparison logic to use the Parameters array exclusively

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
testdata/diff/migrate/v5/plan.json	Updates source fingerprint hash for test data
testdata/diff/create_procedure/drop_procedure/plan.json	Updates source fingerprint hash for procedure test
testdata/diff/create_procedure/alter_procedure/plan.json	Updates source fingerprint hash for procedure test
testdata/diff/create_function/drop_function/plan.json	Updates source fingerprint hash for function test
testdata/diff/create_function/alter_function_same_signature/plan.json	Updates source fingerprint hash for function test
testdata/diff/create_function/alter_function_different_signature/plan.json	Updates source fingerprint hash for function test
testdata/diff/create_function/add_function/plan.txt	Adds new parameter note varchar DEFAULT '' to function signature
testdata/diff/create_function/add_function/plan.sql	Adds new parameter note varchar DEFAULT '' to function SQL
testdata/diff/create_function/add_function/plan.json	Updates SQL statement with new parameter
testdata/diff/create_function/add_function/new.sql	Adds new parameter to function definition
testdata/diff/create_function/add_function/diff.sql	Shows diff with new parameter added
ir/parser.go	Removes code that builds Arguments and Signature strings from parameters
ir/normalize.go	Removes signature normalization and updates parameter normalization
ir/ir.go	Removes Arguments/Signature fields and adds GetArguments() method
ir/inspector.go	Removes population of Arguments and Signature fields
internal/diff/procedure.go	Updates to use Parameters array exclusively
internal/diff/function.go	Updates to use GetArguments() method and Parameters array
internal/diff/diff.go	Updates function key generation to use GetArguments()

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