Share prefiltering struct

[javitonino]

Instead of cloning the prefiltering results a bunch of times, pass a pointer to it.

Notes:

• Mixing resource_filters with any other kind of filter was kind of broken. The rust query planner just appended the results of the prefilter query to the existing key_filters, so it made an OR of them (it should be an AND). This PR fixes it by moving the resource filter to the prefilter.
• The prefilter cannot be easily passed inside the Paragraph/VectorSearchRequest due to being a pointer. This is an implementation detail of the QueryPlanner and could be fixed, but this PR is big enough as it is to add a refactor of the QueryPlanner.
• Removed key_filters from suggest, it was not exposed to the nucliadb API, so removing it from nidx API as well.
• Moved "fields" filter to the prefilter. The is it to make future indexing in nidx_vector easier (no longer have to implement this). All resource filters should be in the prefilter.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.84%. Comparing base (06c0287) to head (7ddacd4).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2858      +/-   ##
==========================================
- Coverage   86.85%   86.84%   -0.01%     
==========================================
  Files         382      382              
  Lines       24161    24161              
==========================================
- Hits        20984    20983       -1     
- Misses       3177     3178       +1     

Flag	Coverage Δ
nucliadb	75.37% <ø> (ø)
nucliadb-ingest	40.97% <ø> (ø)
nucliadb-reader	42.73% <ø> (+0.01%)	⬆️
nucliadb-search	44.30% <ø> (ø)
nucliadb-standalone	47.36% <ø> (ø)
nucliadb-train	45.50% <ø> (ø)
nucliadb-writer	46.89% <ø> (+0.01%)	⬆️
nucliadb_dataset	55.45% <ø> (ø)
nucliadb_models	84.86% <ø> (ø)
nucliadb_sdk	89.67% <ø> (ø)
nucliadb_telemetry	86.56% <ø> (ø)
nucliadb_utils	83.79% <ø> (ø)

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