Expose shared column rename access for table and view actions

[minleejae]

Purpose

Let consumers inspect and edit table, view and materialized-view column renames through one API.

Current design (As-is)

Table column renames store their source and target in columnOldName and columnName; relation actions use columnName and newName. Consumers must distinguish these representations. Master already provides the separate ColumnDefaultAction API.

Target design (To-be)

Expose active renames through AlterExpression.getColumnRename() and ColumnRenameAction, with editable sourceName and targetName accessors. Delegate to existing AST fields so edits through either API remain visible through the other. Preserve identifier quoting and the optional COLUMN keyword; unrelated operations return null.

RelationAlterAction implements both ColumnRenameAction and the existing ColumnDefaultAction, retaining each operation's filtered lookup. Preserve parser result classes and existing public signatures; grammar and dialect acceptance are unchanged. Add a usage example.

Validation

After merging master at 40ed289b, the full Java 17 Gradle check passed: 9,852 tests total, 9,827 passed, 25 skipped, zero failures. All 16 rename tests and 17 column-default tests passed. Coverage includes common/legacy accessor edits, quoted names, inactive operation state, rendering and reparsing. Grammar choice-conflict checks, Spotless, Checkstyle, PMD, SpotBugs and coverage verification passed.

GitHub CI at 5cc52bb1 also passes: Codacy, grammar conflicts, and Gradle/Maven checks on Linux, macOS and Windows.

[manticore-projects]

Please resolve conflicts.

[manticore-projects]

Thank you!