[Php80] Skip loose comparisons that differ from strict on StrStartsWithRector and StrEndsWithRector

[guillaume-sainthillier]

Some loose comparisons handled since #3246 don't behave like str_starts_with() / str_ends_with():

var_dump(strpos('abc', 'x') == 0);            // true, false == 0
var_dump(str_starts_with('abc', 'x'));        // false

var_dump(substr('x+1', -2) == '01');          // true, '+1' == '01' compares as numbers
var_dump(str_ends_with('x+1', '01'));         // false

Change:

• strpos() == 0 / != 0: skipped
• substr(...) == $needle / !=: only refactored when the needle is a non-numeric string literal, where == behaves like ===
• strncmp() / substr_compare() loose comparisons: unchanged, they always return an int

Follow-up to #8641, which does the same for StrContainsRector / MbStrContainsRector.

[TomasVotruba]

Can you revert this? While technically it's correct removal, in legacy projects where this change would be valid most people use ==.

[guillaume-sainthillier]

Closing, as it follows the same loose-comparison reasoning that was declined in #8641. Thanks!