[bazel] Add support for multiple tblgen outputs

[keith]

Required after #167700

This adds yet another format for tbl_outs where you pass the list of opts, and a list of outputs (where previously you could only have 1 output). In that case all outputs must be produced, but the first is used for the -o arg since tblgen is generating the other names based on that single argument.

[keith]

this doesn't work as is because the case where this is used today writes #includes to the file that are relative to bazel-bin and are not valid later on without some more includes / strip_include_prefix usage

[keith]

big reformat change here required by buildifier, but this was an automated swap from dictionary to the tuple format

[keith]

i think that we'll need to do something smarter for tblgen's #include path creation since right now it looks like this:

#include "bazel-out/cfg/bin/external/+llvm_configure+llvm-project/llvm/lib/Target/AMDGPU/R600GenRegisterInfoTargetDesc.inc" 

but likely we want this:

#include "llvm/lib/Target/AMDGPU/R600GenRegisterInfoTargetDesc.inc" 

i think the assumption was the latter path would also match the argument to tblgen itself, and that assumption doesn't hold with bazel