feat: Add additional PHP locales

[musaabhasan]

Description

Adds additional UTF-8 locales to the PHP containers so developers can test non-English and RTL locale formatting without patching Dockerfiles locally.

This keeps en_US.UTF-8 as the default environment locale and adds generated support for:

• de_DE.UTF-8
• fr_FR.UTF-8
• es_ES.UTF-8
• ar_AE.UTF-8
• he_IL.UTF-8

Fixes #219.

Testing Instructions

1. Check out this pull request.
2. Build a PHP container, for example tbuild php-8.4.
3. Start or shell into the container.
4. Run locale -a and verify the added locales are available.
5. Repeat with another PHP version if needed.

Checklist

• Does what the author says it will do
• Testing instructions are provided
• Commit messages make sense and follow the conventional commit standard
• No identified security issues
• No identified maintenance issues
• Any third-party libraries/dependencies use the MIT or Apache 2.0 license
• Changes made are backwards compatible and will not break existing setups
• Changes to scripts in the bin/ directory run correctly on both MacOS and WSL
• Changes to containers can be built locally sucessfully (e.g. via tbuild container && tup container)
• Containers/images are compatible with both AMD64 (Windows) and ARM64 (MacOS)
• Changes made to config.php are compatible with our oldest supported Totara version, our newest Totara version, and Moodle

Local verification:

• git diff --check
• Confirmed all PHP Dockerfiles include the added locale entries.

Container builds were not run locally because Docker is not available in this environment.