Verify bundled deps using CI

Description

I am the author of https://github.com/php/php-src/blob/7db647dd99/.github/actions/verify-generated-files/action.yml and I would be happy if this integrity concept can be extended also to all extenal/bundled deps like PCRE [1], Unicode tables [2] etc.

The expected behaviour is zero changes after the update is run. This will prevent hiding bad code and prevent human mistakes.

• [1] PCRE2 https://github.com/php/php-src/pull/14498
• [2] Unicode tables https://github.com/php/php-src/pull/7502#issue-1000424830 /w update steps described
• [3] XSSE https://github.com/php/php-src/pull/18413
• [4] uriparser https://github.com/php/php-src/pull/19711
• [5] IR https://github.com/php/php-src/commit/2ff7a18bdc8e1ce184c8df312fe87a178f775761
• [6] timelib https://github.com/php/php-src/commit/a0329dbab009d984926f8817359ba5d83195d960 - https://github.com/derickr/timelib/tags
• [7] xxHash https://github.com/php/php-src/pull/20064
• [8] https://github.com/php/php-src/tree/master/ext/fileinfo/libmagic
• [9] https://github.com/php/php-src/tree/master/ext/standard/libavifinfo https://github.com/php/php-src/pull/21250
• [10] https://github.com/php/php-src/tree/master/ext/mbstring/libmbfl
• [11] https://github.com/php/php-src/tree/master/ext/bcmath/libbcmath
• [12] https://github.com/php/php-src/tree/master/ext/dba 3x libs
• [13] https://github.com/php/php-src/tree/master/ext/hash/murmur (impossible - https://github.com/php/php-src/pull/6059#issuecomment-692012970)
• [14] https://github.com/php/php-src/tree/master/ext/hash/sha3
• [15] https://github.com/php/php-src/tree/master/ext/lexbor/lexbor
• [16] https://github.com/php/php-src/tree/master/ext/dom/lexbor
• [17] https://github.com/php/php-src/tree/master/ext/gd/libgd

This was probably not done yet to not slow down the testing pipelines. The solution is to run the integrity verification of the external sources as a separate workflow only when the source files are changed and always in nightly.

Start with .github/actions/verify-generated-files/action.yml and review the unchecked bundled-dependency directories listed in the issue, including IR, libmagic, libavifinfo, libmbfl, libbcmath, and libgd. Define the separate workflow's changed-source and nightly behavior, then verify that each applicable update produces zero changes after its integrity check.