Better handling of nested meta apps

[BrianPugh]

@AngellusMortis can you play around with this? I think the following script (along with this PR) is kind of what you want:

from cyclopts import App, Parameter
from typing import Annotated

app_1 = App()

@app_1.meta.default
def meta_1(*tokens: Annotated[str, Parameter(show=False, allow_leading_hyphen=True)]) -> None:
    """This is app1_meta's help."""
    print("child meta")
    app_1(tokens)

@app_1.command
def test() -> None:
    """"app_1 test" help string."""
    print("app_1 test body")

app = App()
app.command(app_1.meta, name="app1")

@app.meta.default
def meta(*tokens: Annotated[str, Parameter(show=False, allow_leading_hyphen=True)]):
    print("parent meta")
    app(tokens)

if __name__ == "__main__":
    app.meta()

Comments:

• meta apps don't execute for --help. This is intentional as frequently expensive operations are performed in a meta app, such as connecting to an external resource (like a database).
• meta apps do execute during conventional command execution.
• The tokens in the meta signature is copied from the meta app docs.

Addresses #290.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.99%. Comparing base (a898634) to head (840a197).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #291      +/-   ##
==========================================
+ Coverage   93.83%   93.99%   +0.15%     
==========================================
  Files          26       26              
  Lines        3019     3030      +11     
  Branches      636      639       +3     
==========================================
+ Hits         2833     2848      +15     
+ Misses         90       88       -2     
+ Partials       96       94       -2     

Flag	Coverage Δ
unittests	93.99% <100.00%> (+0.15%)	⬆️

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[AngellusMortis]

Looks like it works!

[BrianPugh]

I'll be trying to do a patch release this weekend including this; I want to get some other fixes in with it.