This PR enables transforming nondependent `let`s into `have`s in a
number of contexts: the bodies of nonrecursive definitions, equation
lemmas, smart unfolding definitions, and types of theorems. A motivation
for this change is that when zeta reduction is disabled, `simp` can only
effectively rewrite `have` expressions (e.g. `split` uses `simp` with
zeta reduction disabled), and so we cache the nondependence calculations
by transforming `let`s to `have`s. The transformation can be disabled
using `set_option cleanup.letToHave false`.
Uses `Meta.letToHave`, introduced in #8954.
This PR fixes (1) an issue where private names are not unresolved when
they are pretty printed, (2) an issue where in `pp.universes` mode names
were allowed to shadow local names, (3) an issue where in `match`
patterns constants shadowing locals wouldn't use `_root_`, and (4) an
issue where tactics might have an incorrect "try this" when
`pp.fullNames` is set. Adds more delaboration tests for name
unresolution.
It also cleans up the `delabConst` delaborator so that it uses
`unresolveNameGlobalAvoidingLocals`, rather than doing any local context
analysis itself. The `inPattern` logic has been removed; it was a
heuristic added back in #575, but it now leads to incorrect results (and
in `match` patterns, local names shadow constants in name resolution).
