[9.x] Fixes blade escaped tags issue

[imanghafoori1]

This fixes #45915

In the added test there are 4 matches, in the second replacement @@endforeach with @endforeach in the second replacement.

Then the final replacement searches for @endforeach to replace it with the compiled version, but it finds what was produced by the previously escaped tag because it starts the search from the beginning of the string.

Solution:

Logically when replacing the matches found by REGEX one after the other using Str::replaceFirst, we have to continue from where we last left off.

[taylorotwell]

Are all these substr_replace, strlen calls going to work if there are multi-byte characters in the template?

[imanghafoori1]

@taylorotwell I will design some tests for those cases.

[imanghafoori1]

@taylorotwell It works ok with emojis or other 3-bit chars but it needs some testing, because if someone changes strpos to mb_str_pos it will break;