Queue was renamed to queue in Python 3:
https://docs.python.org/3/whatsnew/3.0.html#library-changes

We require Python >= 3.8.

This code in principle needs to match the one in libc++ but hasn't been updated to account for
LIBCXX_LIBDIR_SUBDIR so tests don't work if LLVM is built with it specified.

Fixes: ed155f3f237a7e3a3e40a84d815225d27e83f0db

Right now, cross-building `lldb` means either installing a native
`lldb-tblgen` by hand (non-trivial, as CMake is painful) or first
building all of native clang because of how the CMake rules work, which
is not fun.

In keeping with the pattern established by llvm-tblgen and clang-tblgen,
install lldb-tblgen to ease cross-compilation.

Co-authored-by: Ross Burton <ross.burton@arm.com>

This PR updates the tablegen emitter for command options to support a
simplified syntax to underline the mnemonic. Previously, you had to
write `${ansi.underline}<L>${ansi.normal}`, where `<L>` is the mnemonic.
This really hurt the readability of the description. With this PR, you
can write `${<L>}` instead.

[lldb] Rename RecursiveDecentFormatter to RecursiveDescentFormatter (NFC)

Necessary argument after
https://github.com/llvm/llvm-project/commit/7dc7c155251c0008d5d59b84f0c9056365740f11

Co-authored-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>

This change is required as a result of the changes made in D132642
(bb26ebb4d18c1877cc6fd17aa803609abeb95096).