logging IID subsampling

[handwerkerd]

I'm still mixed on what to do with #56, but I'm realizing that PR has two parts. It both lets users set the subsampling values and it logs the estimated value. I not sure if it's worth letting users set the value, but we really want this information logged and I don't want to hold up that part. Here's a PR that just logs the info. If it looks good, I'd like to see this merged soonish. I'll open a paired PR for tedana so that the values will be stored with the tedana outputs.

[codecov-commenter]

Codecov Report

Patch coverage: 80.00% and project coverage change: -0.21 :warning:

Comparison is base (45837f9) 90.26% compared to head (feec953) 90.06%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #57 +/- ## ========================================== - Coverage 90.26% 90.06% -0.21% ========================================== Files 3 3 Lines 298 302 +4 ========================================== + Hits 269 272 +3 - Misses 29 30 +1 ``` | [Impacted Files](https://app.codecov.io/gh/ME-ICA/mapca/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ME-ICA) | Coverage Δ | | |---|---|---| | [mapca/mapca.py](https://app.codecov.io/gh/ME-ICA/mapca/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ME-ICA#diff-bWFwY2EvbWFwY2EucHk=) | `86.70% <80.00%> (-0.26%)` | :arrow_down: |

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[handwerkerd]

@eurunuela We don't have the 2 reviewer rule on mapca so, unless @tsalo wants to take a look, just confirm I can merge. We are supposed to have 2 approving reviews for https://github.com/ME-ICA/tedana/pull/951

[eurunuela]

This PR is really simple. I think 1 review is enough.