Replace else branches in Sql with guard clauses and match

[simon-mundy]

Depends on #219. Until the earlier PRs in this series merge, this diff also shows their commits; the change here is the last commit, "Replace else branches in Sql with guard clauses and match".

Clears all 53 no-else-clause Mago lint findings in src/Sql.

Changes

• If/elseif chains that pick a value become match (true) expressions: option rendering in AlterTable and CreateTable, argument wrapping in Expression, In, Operator and PredicateSet, join names in AbstractSql::processJoin(), and column aliases and order direction in Select.
• Other branches return or continue early instead: the where() and having() setters, Insert::values(), the bound-parameter loops in Insert and Update, Select::group() and Select::order(), and AbstractSql::resolveTable().
• AbstractSql gains a private quoteJoinTableIdentifier(), so processJoin()'s match stays flat.
• New tests cover a join on a TableIdentifier without a schema, and resolveTable() with a null or empty table. Neither path had a test.
• Lint and analyzer baselines are regenerated; only src/Sql entries change.

Breaking changes

None.

mago format, mago lint, mago analyze and the unit tests pass, and every changed line is covered.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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