Allow handle() to be an initializer.

[bckohan]

Should be able to decorate handle() with initialize. This would allow you to do something like:

from click import get_current_context
from django_typer import TyperCommand, initialize, command


class Command(TyperCommand):
    
    @initialize(invoke_without_command=True)
    def handle(self):
        if (ctx := get_current_context(silent=True)) and ctx.invoked_subcommand:
            return
        
        # if we're here a subcommand was not invoked
        return 'handle'

    @command()
    def subcommand(self):
        return 'subcommand'

Which would allow:

./manage.py command
handle
./manage.py command subcommand
subcommand

And:

from django_typer import get_command

get_command('command')()
'handle'

You currently get an exception if you try to wrap handle in initialize(), which is a borderline bug.