Custom commands

[ahopkins]

This adds the ability to add commands to the sanic CLI.

@app.command
async def foo(one, two: str, three: str = "..."):
    logger.info(f"FOO {one=} {two=} {three=}")


@app.command
def bar():
    logger.info("BAR")


@app.command(name="qqq")
async def baz():
    logger.info("BAZ")

These are invoked using

sanic server:app exec <command> [--arg=value]