Meta: Cleanup stale rules from .gitignore

The wild card rules at the top of the .gitignore came from a time when
the build wrote back to the git repository and placed files right next
to the source. (Original commit that introduced them 37c27e2e, they were
later consolidated into the root .gitignore in 802d4dc) We have since
moved to cmake, and these rules have become obsolete, and they just
cause issues where we need to go and add negations for these rules in
order for things to work.

A previous change attempted to remove the top wild card rules (PR #4565)
but it was later reverted, as they forgot to remove the top ignore
everything rule '*', so all files were ignored. This change just removes
all of these rules that no longer make sense, restoring a bit of sanity.

*.o,*.d,*.a rules were also from when the build wrote to the repository,
they are now defunct. The same goes for the *Endpoint.h and CMakeFiles
rules.

The lowercase build directory can be removed as we've standardized on
the uppercase 'Build' directory as the root of the build output dir.

.gitignore

@@ -1,17 +1,3 @@
-*
-!*.*
-!*/
-!Makefile
-!LICENSE
-!Base/**
-!Meta/ShellCompletions/**
-
-*.o
-*.ao
-*.a
-*.so
-*.d
-
 *.swo
 *.swp
 *.config
@@ -25,8 +11,6 @@
 *.autosave
 Meta/Lagom/build
 Build
-build
-CMakeFiles
 Toolchain/Tarballs
 Toolchain/Build
 Toolchain/Local
@@ -37,7 +21,6 @@ compile_commands.json
 .cache
 .clang_complete
 .clangd
-*Endpoint.h
 .idea/
 cmake-build-debug/
 sync-local.sh