[WIP] - Simulation updates

[TomDonoghue]

This is an update through the new simulation functionality added in #329

Most of the updates are cleaning up and improving consistency across the sim module. This includes moving some functions around and re-organization sim sub-modules. A notable update is the adding simulation I/O functionality, so that simulations can be saved and loaded.

[ryanhammonds]

Sorry for the delay in reviewing this!

I read through everything here, except for the tests. I think this and the last, related PR, will be useful for running parameter grids of simulations! I left minor comments but everything looked good at a high level.

I was working on something similar here a while ago. The approach here accomplishes the same. I like that you've added parameter sampling too.

The only other thing, that doesn't necessarily need to be addressed here but maybe for something in the future, is parallelization over grids. I think here iterates over sets of parameters serially, maybe a multiprocessing pool could be used if scaling is a concern.

[codecov]

Codecov Report

Attention: Patch coverage is 98.26690% with 10 lines in your changes missing coverage. Please review.

Project coverage is 98.24%. Comparing base (e494f93) to head (e1f186f).
Report is 36 commits behind head on main.

Files with missing lines	Patch %	Lines
neurodsp/sim/generators.py	83.33%	3 Missing ⚠️
neurodsp/sim/io.py	95.94%	3 Missing ⚠️
neurodsp/sim/params.py	98.07%	1 Missing ⚠️
neurodsp/sim/signals.py	98.30%	1 Missing ⚠️
neurodsp/sim/utils.py	0.00%	1 Missing ⚠️
neurodsp/utils/checks.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #336      +/-   ##
==========================================
+ Coverage   98.02%   98.24%   +0.22%     
==========================================
  Files         110      115       +5     
  Lines        3995     4327     +332     
==========================================
+ Hits         3916     4251     +335     
+ Misses         79       76       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[TomDonoghue]

@ryanhammonds - thanks for checking in on this!

I should have totally had a look what was available in ndspflow - it totally slipped my mind to do so! At some point we should work through what is available where and consider consolidating / linking out to other implementations etc.

Also agreed on adding parallel support - I think that would be a great extension!

For now, I'll merge this in!