Add --join-on-indent option to indent multi-keyword join ON clauses

[edjubert]

What

Add a new option --join-on-indent that indents the ON clause continuation lines (AND/OR) of a multi-keyword join (e.g. LEFT OUTER JOIN) one level below the join keyword.

The option is off by default — the existing behavior is fully preserved.

Without the option (default, unchanged)

SELECT
    tyap.tyap_code
FROM
    tyap
    LEFT OUTER JOIN ab_frap appel ON appel.frap_tyap_code = tyap.tyap_code
    AND appel.frap_imme_no = tyap.tyap_imme_no

With --join-on-indent

SELECT
    tyap.tyap_code
FROM
    tyap
    LEFT OUTER JOIN ab_frap appel ON appel.frap_tyap_code = tyap.tyap_code
        AND appel.frap_imme_no = tyap.tyap_imme_no

Why

When a join is spelled with several keywords (LEFT OUTER JOIN, FULL JOIN, …), pgFormatter steps the indentation back once per keyword, so the ON clause continuation lines end up at the same level as the join keyword. Some style guides prefer the AND/OR continuation lines to be indented one level below the join keyword. This option provides that style without changing the default output.

Implementation

• lib/pgFormatter/Beautify.pm: new join_on_indent option (POD, qw() list, set_defaults), and the join step-back condition now only skips the per-keyword step-back when the option is on.
• lib/pgFormatter/CLI.pm: --join-on-indent CLI flag, config mapping, and help text.
• t/test-files/ex85.sql + t/test-files/expected/ex85.sql: regression test covering LEFT OUTER JOIN, INNER/CROSS/NATURAL/RIGHT/FULL JOIN, and plain JOIN/LEFT JOIN, run with --join-on-indent.

Tests

• prove -lv t/ passes (93 tests). The existing ex1.sql (which contains a LEFT OUTER JOIN … ON … AND …) still passes because the default behavior is unchanged.
• Output is idempotent with the option enabled.

[darold]

@edjubert , commit 1b99e6e now apply this formatting as default so the option have been removed from your patch.