[llvm] [Dexter] Normalise the "tools directory" into a list of tools (PR #128544)

[Orlando Cazalet-Hyams via llvm-commits]

https://github.com/OCHyams commented:

SGTM, hurray for simplifying (and deleting) things. Got a couple of inline nits though.

https://github.com/llvm/llvm-project/pull/128544