Adds PHP 8.4 compatibility

[marcing]

• Adds necessary changes for achieving PHP 8.4 compatibility
• Switches PEAR to github, because PEAR repository was removed and no longer works with composer v2
• Removes PHP 5.3 -> 7.0 compatibility due to lack of syntax that would work for both PHP <= 7.0 and 8.4+
• Removes E_STRICT, which is triggers deprecated error

Edit: This pull request will be split into specific ones.

[glensc]

In my opinion, this pr should be rejected:

1. No description
2. The actual diff does more than described in the title
3. alert! removes things, not backward compatible

It would be wasting maintainers' time trying to reverse engineer the changes description from the diffs

Ideally, each change should be submitted as a separate pr, and pr describes the changes.

Note: I'm not a maintainer of this project (but I am elsewhere).

[marcing]

@glensc

1. Updated the description
2. All the changes are necessary to make it work with PHP 8.4, it does nothing more (please see new description)
3. it removes E_STRICT, because it got removed from PHP

It's part of pull request for zf1 and without it the tests fail:
zf1s/zf1#198

Cheers