fix(php): accept short names in php_extensions_custom

[faisalahammad]

Summary

Lets users write a plain list of short names in php_extensions_custom instead of the verbose php{{ php_version }}-<name> dict form. The legacy dict form is still accepted.

Fixes #1666

Changes

roles/php/defaults/main.yml

Before:

php_extensions_custom: {}
php_extensions: "{{ php_extensions_default | combine(php_extensions_custom) }}"

After:

php_extensions_custom: []
php_extensions_custom_normalized: "{{ php_extensions_custom | php_extensions(php_version, apt_package_state) }}"
php_extensions: "{{ php_extensions_default | combine(php_extensions_custom_normalized) }}"

Why: combine() needs a dict on the right side. A new php_extensions filter coerces list input to {php<version>-<name>: <state>} and passes dict input through unchanged.

lib/trellis/plugins/filter/filters.py

After:

def php_extensions(value, php_version, package_state):
    if isinstance(value, dict):
        return value
    if isinstance(value, list):
        return {f"php{php_version}-{name}": package_state for name in value}
    return {}

Why: Single source of truth for the list vs dict shape decision.

roles/common/tasks/main.yml

Before: one package_vars dict, all entries checked with rejectattr('value', 'mapping'). php_extensions_custom was treated as dict-only.

After: split into package_vars_dict_only (mapping check) and package_vars_list_or_dict (mapping OR non-string sequence). The wrong-format list is the union of both wrong-key sets, so a string or int input to php_extensions_custom is still rejected.

Why: is sequence in Jinja2 is also true for strings, so the new predicate computes the valid-key set explicitly.

Testing

Test 1: list form accepted

1. Set php_extensions_custom: [soap, gd] in group_vars/all/main.yml.
2. Run pytest -q -ra tests/templates.
   Result: 6 new tests in tests/templates/test_php_extensions_custom.py pass, plus the 9 pre-existing tests.

Test 2: dict form still works

1. Set php_extensions_custom: { \"php{{ php_version }}-soap\": \"{{ apt_package_state }}\" }.
2. Run pytest -q -ra tests/templates and ansible-playbook --syntax-check -e env=development server.yml.
   Result: same merged dict as before the change. Syntax check clean.

Test 3: bad input rejected

1. Set php_extensions_custom: \"oops\" (a bare string).
2. Run any play that includes the common role.
   Result: verify task fails with a message naming php_extensions_custom as a wrong-format variable.