feat: New curp conflict pool

[bsbds]

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?)

  First PR of #668.

  Implements new speculative pool and uncommitted pool in curp.

• what changes does this pull request make?

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.41121% with 71 lines in your changes are missing coverage. Please review.

Project coverage is 75.62%. Comparing base (e9008c0) to head (e65467d). Report is 1 commits behind head on master.

Files	Patch %	Lines
...rates/curp/src/server/conflict/uncommitted_pool.rs	69.81%	31 Missing and 1 partial :warning:
crates/curp/src/server/conflict/tests.rs	84.57%	27 Missing and 4 partials :warning:
crates/curp/src/server/conflict/mod.rs	89.18%	4 Missing :warning:
crates/curp/src/server/conflict/spec_pool_new.rs	94.66%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #675 +/- ## ========================================== + Coverage 75.45% 75.62% +0.17% ========================================== Files 176 180 +4 Lines 26515 26938 +423 Branches 26515 26938 +423 ========================================== + Hits 20006 20371 +365 - Misses 5297 5346 +49 - Partials 1212 1221 +9 ```

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