Add enforcement for np.sort and np.argsort

[yuema137]

This PR enforces deterministic sorting behavior by implementing the sort_enforcement module. Specifically, it:

1. Makes mergesort the default sorting algorithm
2. Disables non-deterministic sorting algorithms (quicksort and heapsort) to prevent their usage
3. Wraps np.sort and np.argsort to enforce the behaviors mentioned above

The implementation is robust to import order - the enforcement takes effect whenever strax is imported, regardless of whether numpy is imported before or after. This ensures consistent sorting behavior across all strax operations, addressing the non-deterministic sorting issues reported in #916.

A unit test is also added accordingly.

[coveralls]

coverage: 90.074% (+0.009%) from 90.065%
when pulling 248a2a8 on set_default_as_mergesort
into c3dd2e1 on master.

[yuema137]

Unfortunately, the kind for np.sort is hard-coded as quicksort in numba now:
https://github.com/numba/numba/blob/0f363d1b2dd19f2aa1a8cec5f0a99c3dd95512f8/numba/np/arrayobj.py#L6524

For np.argsort, mergesort and quicksort are both supported though.

So we have two options:

1. Make a PR to numba to enable mergesort for np.sort (need to check if it's easy)
2. Move all the sorting in strax outside of the numba decorators (need to check performance)

I'm checking the possibility for both ways.

[dachengx]

#918 (comment)

[dachengx]

I should mention that this PR is following up XENONnT/straxen#1176, for future reference.