[declare] [tactics] Move declare to `vernac`

This PR moves `Declare` to `vernac` which will hopefully allow to
unify it with `DeclareDef` and avoid exposing entry internals.

There are many tradeoffs to be made as interface and placement of
tactics is far from clear; I've tried to reach a minimally invasive
compromise:

- moved leminv to `ltac_plugin`; this is unused in the core codebase
  and IMO for now it is the best place
- hook added for abstract; this should be cleaned up later
- hook added for scheme declaration; this should be cleaned up later
- separation of hints vernacular and "tactic" part should be also done
  later, for now I've introduced a `declareUctx` module to avoid being
  invasive there.

In particular this last point strongly suggest that for now, the best
place for `Class_tactics` would be also in `ltac`, but I've avoided
that for now too.

This partially supersedes #10951 for now and helps with #11492 .

1 files changed, 1 insertions, 1 deletions

diff --git a/plugins/setoid_ring/newring.ml b/plugins/setoid_ring/newring.ml
index 0646af3552..633cdbd735 100644
--- a/plugins/setoid_ring/newring.ml
+++ b/plugins/setoid_ring/newring.ml
@@ -150,7 +150,7 @@ let decl_constant na univs c =
   let open Constr in
   let vars = CVars.universes_of_constr c in
   let univs = UState.restrict_universe_context ~lbound:(Global.universes_lbound ()) univs vars in
-  let () = Declare.declare_universe_context ~poly:false univs in
+  let () = DeclareUctx.declare_universe_context ~poly:false univs in
   let types = (Typeops.infer (Global.env ()) c).uj_type in
   let univs = Monomorphic_entry Univ.ContextSet.empty in
   mkConst(declare_constant ~name:(Id.of_string na)