Version 1 of flowMC code, adds custom MALA kernel too

[kdesoto-astro]

Change Description

Code Quality

• I have read the Contribution Guide
• My code follows the code style of this project
• My code builds (or compiles) cleanly without any errors or warnings
• My code contains relevant comments and necessary documentation

[codecov]

Codecov Report

Merging #36 (5610f2e) into main (42d00b0) will increase coverage by 6.66%.
The diff coverage is 1.07%.

@@            Coverage Diff             @@
##             main      #36      +/-   ##
==========================================
+ Coverage   23.03%   29.70%   +6.66%     
==========================================
  Files          11       18       +7     
  Lines        2097     2377     +280     
==========================================
+ Hits          483      706     +223     
- Misses       1614     1671      +57     

Impacted Files	Coverage Δ
src/superphot_plus/custom_mala.py	0.00% <0.00%> (ø)
src/superphot_plus/fit_flowmc.py	0.00% <0.00%> (ø)
src/superphot_plus/constants.py	100.00% <100.00%> (ø)

... and 14 files with indirect coverage changes

[kdesoto-astro]

Part 1 - without complete documentation/test cases but working. Merging so I can create an updated branch to finish this up