Refactor mk_and and mk_app to use std::span API (#8285)

* Initial plan

* Refactor mk_and and mk_app to use std::span

- Made mk_and(unsigned num_args, expr * const * args) private
- Added new public mk_and(std::span<expr* const> args) method
- Added new public mk_app(family_id fid, decl_kind k, std::span<expr* const> args) method
- Updated all convenience overloads to use std::span version
- Updated all external call sites to use the new std::span API

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

* Fix remaining test files to use std::span API

- Updated src/test/sorting_network.cpp
- Updated src/test/ho_matcher.cpp with explicit cast to resolve ambiguity

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

* Revert overlapping changes superseded by PR #8286

Reverted 30 files to match the state from PR #8286 (commit ebc0688) which refactored mk_and/mk_or call sites to use vector overloads. This supersedes the std::span changes in those files.

Retained std::span changes in files unique to this PR:
- Core API changes (ast.h, ast.cpp)
- Files not affected by PR #8286 (api_context.cpp, ast_util.cpp, bool_rewriter.h, datatype_rewriter.cpp, dom_simplifier.cpp, factor_rewriter.cpp, pb2bv_rewriter.cpp, quant_hoist.cpp, spacer_cluster_util.cpp, sortmax.cpp, array_axioms.cpp, smtfd_solver.cpp, goal.cpp, ho_matcher.cpp, qe_arith.cpp, sorting_network.cpp)
- Special case in hnf.cpp where both PRs modified different lines

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

src/api/api_context.cpp

@@ -251,7 +251,7 @@ namespace api {
             save_ast_trail(exprs[0]);
             return exprs[0];
         default: {
-            expr * a = m().mk_and(num_exprs, exprs);
+            expr * a = m().mk_and(std::span<expr* const>(exprs, num_exprs));
             save_ast_trail(a);
             return a;
         } }