T17055 phalcon alignment

[niden]

Hello!

• Type: bug fix
• Link to issue: [NFR]: cphalcon - phalcon alignment #17055

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Small description of change:

• Alignment with v6;
• docblocks;
• sorting;
• return types;
• minor fixes (image watermark opacity calc, serializer/helpers, readonly-becoming-mutable, ACL local access).

Thanks