Feature request: Include `clangd`, `clang-tidy`, and `clang-format` binaries

[ormandi]

Context:
Starting with version 1.5.0 of toolchains_llvm, the clangd, clang-tidy,
and clang-format binaries are now hardcoded requirements for the
toolchain (please see toolchain/internal/common.bzl:40-43
for more details). These are part of the _toolchain_tools list and must be
present in the LLVM distribution.

Without them, the build fails with the following errors:

  ERROR: /some/path/BUILD:8:8: Compiling some/source.cc failed: missing input file '@@toolchains_llvm++llvm+llvm_toolchain//:bin/clang-format'
  ERROR: /some/path/BUILD:8:8: Compiling some/source.cc failed: missing input file '@@toolchains_llvm++llvm+llvm_toolchain//:bin/clang-tidy'
  ERROR: /some/path/BUILD:8:8: Compiling some/source.cc failed: missing input file '@@toolchains_llvm++llvm+llvm_toolchain//:bin/clangd'
...
  ERROR: Build did NOT complete successfully

The MaterializeInc minimal distribution currently excludes these to keep the
package size small.

Feature request:
Would it be possible to include these in future releases? We are hoping that
adding them won't significantly increase the distribution size.

Thank you for your consideration!