chore: add 8.5 support

[stobrien89]

Description of changes:
Fixes PHP 8.5 deprecation warnings and adds 8.5 to test runs, adds Windows unit test workflow, adds JIT to applicable workflows, adds separate Codecov coverage workflow that runs weekly.

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[yenfryherrerafeliz]

I think falling back to empty string in every array access could be problematic, but we can leave this open for discussion.

[yenfryherrerafeliz]

I prefer the idea of evaluating if the key is null and not fallback to make the key an empty string. Why?, because an empty string is also a valid array key and this could cause unexpected behaviors. Also, when setting the key you also fallback to make it empty.

[yenfryherrerafeliz]

For example:

if ($key == null || !isset($this->items[$key])) {
    return null;
}

[stobrien89]

I don't particularly like falling back to an empty string either, but it's official guidance from the deprecation guide:

Using null as an array offset ¶
Using null as an array offset or when calling array_key_exists() is now deprecated. Instead an empty string should be used.

I'll try to come up with a better way around this

[stobrien89]

dug into this a bit further- avoided in areas where checks could be performed in another way, but in this class and MultiRegionClient, we break backward-compatibility if we do anything else. From the PHP Manual:

Null will be cast to the empty string, i.e. the key null will actually be stored under "".

In those classes we were setting/getting '' keys and that's behavior we should retain.

[yenfryherrerafeliz]

I think the extra condition could be redundant?, unless $context may be null?

[stobrien89]

Removed in the latest update

[yenfryherrerafeliz]

I guess this is redundant. The same thing happens after line 561, unless I am missing something?

[stobrien89]

slightly different format: for Linux, it's wrapped in an outer string

[yenfryherrerafeliz]

What does this mean?, customers can't do downloads using access points ARNs on Windows then?

[stobrien89]

possibly. Will need to add to the backlog to investigate. I tried for a while to get this working