Fix mutation operator

[YamLyubov]

Changes:

• If mutation will be applied is decided outside of the retry loop. Previously we were shooting ourselves in the foot trying to defenetly apply a mutation while deciding to apply it with some probability in the loop.
• Also the choice of the mutation type is made outside the loop to collect proper experience for the agent (now the agent can know that the exact mutation type failed to apply to the specified graph).
• Negative reward in case of unsuccesfull mutation is registered only once after several attempt. It prevents the agent of being biased.
• Base mutations now try on different nodes to make any change which makes it possible to remove equality check in the mutation operator.

Proposed changes have shown better results on synthetic task for tree graph (random bandit).
Here is mean results for 20 launches with all implemented base mutations with 50 maximal iterations and 20 min time limit.
It can be seen that new version:

• works faster,
• converge in fewer iterations
• achieves slightly better results (in tertms of mean and std).
  
  

It is a toy experiment but still...

New version results

Old version results

[codecov-commenter]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (46b53a4) 71.94% compared to head (80d51b4) 72.04%.
Report is 4 commits behind head on main.

Files	Patch %	Lines
...ore/optimisers/genetic/operators/base_mutations.py	93.02%	6 Missing ⚠️
...ore/optimisers/genetic/parameters/mutation_prob.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #238      +/-   ##
==========================================
+ Coverage   71.94%   72.04%   +0.10%     
==========================================
  Files         136      136              
  Lines        8127     8164      +37     
==========================================
+ Hits         5847     5882      +35     
- Misses       2280     2282       +2     

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

[kasyanovse]

В строке происходит проверка verifierом сразу после мутации. По идее, эта проверка реализована внутри мутации, ее можно убрать.

UPD: так как эта проверка осуществляется один раз при подготовке начального поколения, то пусть будет.

[kasyanovse]

У меня почему-то в ParentOperator в operators лежат функции, что несериализуемо и неудобно. Может быть хранить там строки, как сделано в кроссовере? Немного потестировал такой вариант у себя, все работает.
Я могу залить оба изменения, которые предложил в последних комментах.