This introduces a TermManager object, which will, in the future, be the
sole object responsible for handling/managing terms and sorts. For now,
all corresponding functions in `cvc5::Solver` are marked as deprecated,
as is constructor `cvc5::Solver::Solver()`, since in the future a solver
instance must be constructed from a term manager instance. Currently, we
maintain a static thread_local term manager instance to not break the
API and continue providing constructor `cvc5::Solver::Solver()`.
Note that this already converts all C++ unit tests to use the
TermManager except for a single test `getStatistics()` in
`test/unit/api/cpp/solver_black.cpp`. Statistics handling is currently
still maintained on the solver level. The statistics we maintain,
however, concern terms only and will eventually be refactored to be
tracked in the NodeManager.
Further note that the Java and Python APIs will be refactored in
separate PRs.
This introduces a general way to use public enums both in the C++ and
the (upcoming) C API. For the C++ case, we now use enum classes rather
than enums for public enums. This also includes definitions for
C API to_string conversions for public enums. C API definitions in
cvc5_types.h are only included from the C API, guarded via a macro
(thus, for now, not included yet when the header is included).
