Refactor divergence check to each sampler

[junpenglao]

Fix #391.

The change end up quite small that it do away divergence check in proposal.py, and compute divergence only when needed (in hmc.py and trajectory.py). The functions in proposal.py is more general than just HMC that we see pattern like:

new_proposal, _ = generate_proposal(state, end_state)

So removing the check would keeps the functions in proposal.py simpler and more focus.

However, we cannot push the check the top most level (ie., it need to remain in trajectory.py), as the information is used during the trajactory building and it is not easy to refactor it away.

[codecov]

Codecov Report

Merging #579 (48acc23) into main (df935cf) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #579   +/-   ##
=======================================
  Coverage   99.14%   99.14%           
=======================================
  Files          49       49           
  Lines        2099     2100    +1     
=======================================
+ Hits         2081     2082    +1     
  Misses         18       18           

Files	Coverage Δ
blackjax/mcmc/hmc.py	100.00% <100.00%> (ø)
blackjax/mcmc/mala.py	100.00% <100.00%> (ø)
blackjax/mcmc/proposal.py	100.00% <100.00%> (ø)
blackjax/mcmc/random_walk.py	100.00% <100.00%> (ø)
blackjax/mcmc/trajectory.py	95.90% <100.00%> (+0.06%)	⬆️

[albcab]

Looks good, makes proposal.py cleaner!