`--enable-error-code code` does not enable some error codes, yet neither are they reported as an invalid error codes

In my understanding, --enable-error-code unreachable should have the same effect as --warn-unreachable. But, instead, it seems to have no effect, and doesn't even produce an error.

$uvx mypy -c "if False: print('hello')"
Success: no issues found in 1 source file

$uvx mypy -c "if False: print('hello')" --warn-unreachable
<string>:1: error: Statement is unreachable  [unreachable]
Found 1 error in 1 file (checked 1 source file)

$uvx mypy -c "if False: print('hello')" --enable-error-code unreachable
Success: no issues found in 1 source file

$uvx mypy -c "if False: print('hello')" --enable-error-code unreachable --warn-unreachable
<string>:1: error: Statement is unreachable  [unreachable]
Found 1 error in 1 file (checked 1 source file)

$uvx mypy -c "if False: print('hello')" --enable-error-code funnyerrorcodenotreal
usage: mypy [-h] [-v] [-V] [more options; see below]
            [-m MODULE] [-p PACKAGE] [-c PROGRAM_TEXT] [files ...]
mypy: error: Invalid error code(s): funnyerrorcodenotreal

Based on my testing, this seems to have been the case since 1.0.0 and maybe before, and thus is not a recent regression.

Beginne bei der mypy-Kommandozeilenverarbeitung für --enable-error-code und --warn-unreachable und verwende den Reproducer im Issue als erste Prüfung. Vergleiche das Verhalten für unreachable mit einem ungültigen Code und füge anschließend gezielte Kommandozeilentests hinzu oder aktualisiere sie, sodass das Aktivieren von unreachable ohne --warn-unreachable funktioniert, während ungültige Codes weiterhin abgelehnt werden.