SKALED-1431 debug_getFutureTransactions call

[dimalit]

Rebased from v3.18.0 to v3.17.2

Test sequence:

1. Add balance for your account to skaled's config.
2. Run skaled with --enable-debug-behavior-apis
3. Send transaction with too big nonce.
4. Send curl -X POST --data '{"id":4,"jsonrpc":"2.0","method":"debug_getFutureTransactions","params":[]}'
5. See your transaction.
6. Repeat the same without --enable-debug-behavior-apis, METHOD_NOT_FOUND error should be returned.

[github-actions]

SUGGESTIONS BEFORE MERGE:

1. Build custom container here: https://github.com/skalenetwork/skaled/actions?query=workflow%3A%22Custom+Docker+and+Binary%22
2. Test it here: https://github.com/skalenetwork/skale-ci-integration_tests/actions?query=workflow%3A%22Skaled+Nightly+Tests%22
3. Edit VERSION file appropriately to your changes!
   See https://skalelabs.atlassian.net/wiki/spaces/SKALE/pages/2444951553/Branching+instructions

[codecov]

Codecov Report

Attention: 187 lines in your changes are missing coverage. Please review.

Comparison is base (8717699) 42.61% compared to head (2a30c8b) 42.63%.
Report is 2 commits behind head on v3.17.2.

Additional details and impacted files

@@             Coverage Diff             @@
##           v3.17.2    #1761      +/-   ##
===========================================
+ Coverage    42.61%   42.63%   +0.01%     
===========================================
  Files          392      392              
  Lines        56973    57036      +63     
===========================================
+ Hits         24281    24317      +36     
- Misses       32692    32719      +27