community/chromium: upgrade to 120.0.6099.71, take over maintainership

it's my problem now. and a fuckton of other changes.

• chromium can no longer be built without non-trivial patches GCC. also it can't be built with clang with libstdc++. now instead of patching shit until it builds with libstdc++ we have to bundle libcxx. this breaks unbundling of the dependencies exposing APIs with C++ std types, like std::string or std::vector.
• no more thin lto. anywhere. now it builds.
• otoh, unbundling more of what's possible now. it built on my machine instead of throwing std::bad_alloc at the end, so I guess this works.
• reorganized patches. more reuse from gentoo, patches over same file merged.