fix(arrow): quote identifiers in generated DDL for Arrow-backed tables (#756)

[adsharma]

Fixes #756

ArrowTableSupport::createViewFromArrowTable, createRelTableFromArrowTable, and createRelTableFromArrowCSR built their CREATE NODE TABLE / CREATE REL TABLE statements by string concatenation, never quoting the Arrow field names or the caller-supplied table names. Many ordinary names (index, order, group, end, default, names with a space, names with a leading digit) are not valid unquoted Cypher identifiers and were rejected by the parser.

Change (src/storage/table/arrow_table_support.cpp):

• New quoteIdent helper (file-scoped in the lbug namespace, matching the existing join and findArrowColumnByName helpers): wraps an identifier in backticks.
• All identifier interpolations in the three CREATE ... TABLE builders are now wrapped in quoteIdent(...): column names, table name, primary-key column, and the FROM/TO endpoint table names in the rel-table builders.
• Bonus fix (same bug pattern): unregisterArrowTable builds a DROP TABLE statement with the same unquoted identifier. Without fixing it, a table created via this PR with a reserved name would have been un-droppable. Now also quoted.

Tests added (3, all pass):

• ArrowNodeTableTest.CreateArrowTableReservedFieldNames — columns named index and value
• ArrowNodeTableTest.CreateArrowTableIrregularFieldNames — columns named my column and 2nd (the harder cases)
• ArrowRelTableTest.CreateArrowRelTableReservedTableName — rel table itself named index

All 50 arrow tests continue to pass; 14 pre-existing skips, 0 regressions.

Release note: callers that previously worked around this bug by pre-quoting Arrow field names with backticks (so the generated DDL happened to be correct) will now get double-quoted identifiers ( `\`index\ ``) and fail. Those backticks should be removed from the Arrow field names.

Out of scope (per the issue author):

• LogicalType::toString() for STRUCT member names is a design call left for a separate look; STRUCT member quoting still fails after this change.
• Backtick-escaping inside Transformer::transformSymbolicName is a separate parser issue; not addressed here.