fix: Parser - Equal key name replace conflict

[CosDiabos]

Description
Fixes the conflict when replacing View Parser {variables} in the provided data with the same key name, even when on different levels.

This fix focus on parse() method, in which the return of parsePair and parseSingle methods are stored independently , then merged together (Pairs with Single), and finally replaced. With this approach, the replacement happens from the Pairs to Single and the output is as expected.

More details and examples in issue #9245

Fixes #9245

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[samsonasik]

Run Rector and cs fix:

vendor/bin/rector && composer cs-fix

also, a test case seems needed.

[samsonasik]

You can rename PR title with fix: prefix

[datamweb]

@CosDiabos To ensure the security and authenticity of your commits, please sign all of them with GPG. This shows others that the commits were genuinely made by you and can be trusted.

For a detailed guide on signing commits with GPG, please refer to gpg-signing-old-commits.

[CosDiabos]

Thank you all for your help!

[michalsn]

@CosDiabos Looks great! We need one last thing - a changelog entry.

Please add it under the Bugs Fixed section, here: https://github.com/codeigniter4/CodeIgniter4/blob/develop/user_guide_src/source/changelogs/v4.5.6.rst

Something like:

Parser: Fixed a bug that caused equal key names to be replaced by the key defined first.

Thanks.

[michalsn]

@CosDiabos Thank you for your first contribution!