yaml parsing (13%)

With flask-session, CKAN now has implicit msgspec dependency. Even if we ignore all the cool possibilities of this library and focus only on really fast parsing, we can improve this number. Here are my local results for yaml and msgspec. For testing, I used config declarations from ckan/config/config_declaration.yaml.

In [10]: %timeit yaml.safe_load(open(filename, "rb").read())
154 ms ± 245 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

In [11]: %timeit msgspec.yaml.decode(open(filename, "rb").read())
10.4 ms ± 40.4 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

@smotornyuk great idea. Sounds like an easy fix to bring that 13% down to 1%.

@amercader I didn't see an easy way to add decorators with click for load_environment and make_flask that are backwards compatible, so I'm leaving it for now. This PR is ready for review.

xychart-beta horizontal
    title "CLI performance improvements"
    x-axis ["ckan user list", "NEW ckan user list", "ckan --help", "NEW ckan --help"]
    y-axis "Speed (invocations/s)" 0 --> 0.8
    bar [.313, .376, .317, .649]

failure looks unrelated, passes locally.

@amercader my preference with make_app and load_environment is to export them in the plugins toolkit and switch all the cli tools to call one of them only when necessary.

That would allow quick handling for catching errors in parameters etc. and involve no hacky special cases for --help or ckan generate config.

External extensions with cli interfaces can check for the existence of the make_app or load_environment and if they aren't there assume make_app has already been called to be compatible with old and new ckans.

WDYT?