GitHub CI reports mypy issues

[christophebedard]

Some mypy issues started being reported by GitHub CI a few weeks ago in tracetools_test, test_tracetools_launch, and tracetools_launch:

tracetools_test/utils.py: note: In function "run_and_trace":
tracetools_test/utils.py:80:31: error: Argument 1 to "append" of "list" has incompatible type "Node"; expected "Trace"  [arg-type]
tracetools_test/utils.py:81:27: error: Argument 1 to "extend" of "list" has incompatible type "list[Action]"; expected "Iterable[Trace]"  [arg-type]

test/test_tracetools_launch/test_trace_action.py: note: In member "_assert_launch_frontend_no_errors" of class "TestTraceAction":
test/test_tracetools_launch/test_trace_action.py:73:16: error: Incompatible return value type (got "LaunchDescriptionEntity", expected "Trace")  [return-value]
test/test_tracetools_launch/test_trace_action.py: note: In member "test_action_context_per_domain" of class "TestTraceAction":
test/test_tracetools_launch/test_trace_action.py:216:13: error: Argument 1 to "assertDictEqual" of "TestCase" has incompatible type "Mapping[str, Iterable[list[Substitution]]] | Iterable[list[Substitution]]"; expected "Mapping[Any, object]"  [arg-type]
test/test_tracetools_launch/test_trace_action.py: note: In member "test_action_substitutions" of class "TestTraceAction":
test/test_tracetools_launch/test_trace_action.py:261:13: error: Argument 1 to "assertDictEqual" of "TestCase" has incompatible type "Mapping[str, Iterable[list[Substitution]]] | Iterable[list[Substitution]]"; expected "Mapping[Any, object]"  [arg-type]
test/test_tracetools_launch/test_trace_action.py: note: In member "test_append_timestamp" of class "TestTraceAction":
test/test_tracetools_launch/test_trace_action.py:345:25: error: "list[Substitution]" has no attribute "startswith"  [attr-defined]

tracetools_launch/actions/ld_preload.py: note: In member "execute" of class "LdPreload":
tracetools_launch/actions/ld_preload.py:84:5: error: Return type "list[Action] | None" of "execute" incompatible with return type "list[LaunchDescriptionEntity] | None" in supertype "Action"  [override]
tracetools_launch/actions/ld_preload.py:86:21: error: List item 0 has incompatible type "Action | None"; expected "Action"  [list-item]
tracetools_launch/action.py: note: In member "context_fields" of class "Trace":
tracetools_launch/action.py:212:16: error: Incompatible return value type (got "Collection[list[Substitution] | Any | str]", expected "Mapping[str, Iterable[list[Substitution]]] | Iterable[list[Substitution]]")  [return-value]
tracetools_launch/action.py: note: In member "_perform_substitutions" of class "Trace":
tracetools_launch/action.py:386:30: error: Incompatible types in assignment (expression has type "str", variable has type "list[Substitution]")  [assignment]
tracetools_launch/action.py:388:34: error: Incompatible types in assignment (expression has type "str", variable has type "list[Substitution]")  [assignment]
tracetools_launch/action.py:388:56: error: Argument 1 to "append_timestamp" has incompatible type "list[Substitution]"; expected "str"  [arg-type]
tracetools_launch/action.py:389:27: error: Incompatible types in assignment (expression has type "str", variable has type "list[Substitution] | None")  [assignment]
tracetools_launch/action.py:391:29: error: List comprehension has incompatible type List[str]; expected List[list[Substitution]]  [misc]
tracetools_launch/action.py:392:32: error: List comprehension has incompatible type List[str]; expected List[list[Substitution]]  [misc]
tracetools_launch/action.py:393:27: error: List comprehension has incompatible type List[str]; expected List[list[Substitution]]  [misc]
tracetools_launch/action.py:400:50: error: Argument 2 to "perform_substitutions" has incompatible type "list[Substitution] | Any | str"; expected "list[Substitution]"  [arg-type]
tracetools_launch/action.py:403:41: error: Argument 1 to "has_libc_wrapper_events" of "Trace" has incompatible type "list[list[Substitution]]"; expected "list[str]"  [arg-type]
tracetools_launch/action.py:405:44: error: Argument 1 to "has_pthread_wrapper_events" of "Trace" has incompatible type "list[list[Substitution]]"; expected "list[str]"  [arg-type]
tracetools_launch/action.py:407:31: error: Argument 1 to "has_dl_events" of "Trace" has incompatible type "list[list[Substitution]]"; expected "list[str]"  [arg-type]
tracetools_launch/action.py:410:63: error: Argument 1 to "has_profiling_events" of "Trace" has incompatible type "list[list[Substitution]]"; expected "list[str]"  [arg-type]
tracetools_launch/action.py:411:65: error: Argument 1 to "has_profiling_events" of "Trace" has incompatible type "list[list[Substitution]]"; expected "list[str]"  [arg-type]
tracetools_launch/action.py: note: In member "execute" of class "Trace":
tracetools_launch/action.py:420:5: error: Return type "list[Action] | None" of "execute" incompatible with return type "list[LaunchDescriptionEntity] | None" in supertype "Action"  [override]