move core 1D asserts to _check_filterbanks in ScatteringBase

[lostanlen]

Fixes #869 by @MuawizChaudhary

don't mind the title of the branch: oversampling is not becoming immutable.
also don't mind the title of the commit: _check_filterbanks belongs in ScatteringBase, not ScatteringBase1D

[MuawizChaudhary]

I'm fine with merging if you are @janden

[codecov-commenter]

Codecov Report

Merging #876 (4c9f8f4) into dev (88a806a) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev     #876      +/-   ##
==========================================
+ Coverage   87.76%   87.80%   +0.03%     
==========================================
  Files          64       64              
  Lines        2232     2238       +6     
==========================================
+ Hits         1959     1965       +6     
  Misses        273      273              

Flag	Coverage Δ
jenkins_main	87.80% <100.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
kymatio/scattering1d/core/scattering1d.py	100.00% <ø> (ø)
kymatio/frontend/base_frontend.py	84.00% <100.00%> (+6.22%)	⬆️
kymatio/scattering1d/frontend/base_frontend.py	97.56% <100.00%> (+0.03%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 88a806a...4c9f8f4. Read the comment docs.

[lostanlen]

@changhongw @cyrusvahidi whoever sees this first, please approve and merge

[lostanlen]

this one goes in pair with #887

[cyrusvahidi]

belle