Support external (i.e. user-defined) trace annotations (#195)

* Support external (i.e. user-defined) trace annotations

- tweaked the python examples to be more balanced
- updated the user-api example to conform to user API changes
- moved the get/set for State and ThreadState to state.{hpp,cpp}
- introduced user-provided trace annotations
- added perfetto python category
- moved coverage impl files around
- created enumerations for mapping category enums to category types
- created enumerations for mapping annotation type enums to annotation values
- moved tracing::add_perfetto_annotations to tracing/annotation.hpp
- utility make_index_sequence_range
- libomnitrace-dl: omnitrace_push_category_region
- libomnitrace-dl: omnitrace_pop_category_region
- libomnitrace-user: omnitrace_user_push_annotated_region
- libomnitrace-user: omnitrace_user_pop_annotated_region
- libpyomnitrace: support extra annotations via annotate_trace config value
  - filename
  - line
  - last attempted instr in bytecode (lasti)
  - argcount
  - num local variables
  - stacksize
- omnitrace-python: -a / --annotate-traces option

* tweak ubuntu-focal workflow

* Fix installation of omnitrace-user headers

* ubuntu-focal-codecov workflow update

- Install texinfo

* Update timemory submodule

source/lib/omnitrace/library/runtime.cpp

@@ -244,55 +244,6 @@ get_preinit_bundle()
     return _v;
 }
 
-namespace
-{
-auto&
-get_thread_state_history(int64_t _idx = utility::get_thread_index())
-{
-    static auto _v = utility::get_filled_array<OMNITRACE_MAX_THREADS>(
-        []() { return utility::get_reserved_vector<ThreadState>(32); });
-
-    return _v.at(_idx);
-}
-}  // namespace
-
-ThreadState&
-get_thread_state()
-{
-    static thread_local ThreadState _v{ ThreadState::Enabled };
-    return _v;
-}
-
-ThreadState
-set_thread_state(ThreadState _n)
-{
-    auto _o            = get_thread_state();
-    get_thread_state() = _n;
-    return _o;
-}
-
-ThreadState
-push_thread_state(ThreadState _v)
-{
-    if(get_thread_state() >= ThreadState::Completed) return get_thread_state();
-
-    return get_thread_state_history().emplace_back(set_thread_state(_v));
-}
-
-ThreadState
-pop_thread_state()
-{
-    if(get_thread_state() >= ThreadState::Completed) return get_thread_state();
-
-    auto& _hist = get_thread_state_history();
-    if(!_hist.empty())
-    {
-        set_thread_state(_hist.back());
-        _hist.pop_back();
-    }
-    return get_thread_state();
-}
-
 bool
 sampling_enabled_on_child_threads()
 {