[MOD-10037] add default scorer in configuration

[JoanFM]

Describe the changes in the pull request

Add DEFAULT_SCORER to configuration to be applied for every type of query

---

Note

Introduce a validated DEFAULT_SCORER config (via FT.CONFIG and Redis CONFIG) and apply it across SEARCH/AGGREGATE/HYBRID when no scorer is specified.

• Configuration:
  • Add DEFAULT_SCORER (FT.CONFIG) and search-default-scorer (Redis CONFIG) with validation against registered scorers and exposure in INFO and config dumps.
  • Store in RSGlobalConfig.defaultScorer; getters/setters, load-time and runtime support; deprecation messages preserved.
• Query Execution:
  • Use global default scorer when SCORER not provided in FT.SEARCH/FT.AGGREGATE/FT.HYBRID (AREQ_ApplyContext, pipeline scorer, LLAPI iterator).
  • Optimizer treats unspecified or BM25STD equivalently for scorer type.
• Extensions/Core:
  • Add Extensions_InitDone(); validate configured default scorer after loading extensions; log/abort on invalid; free on unload.
• Info/Diagnostics:
  • Include default_scorer in runtime info and formatted config string.
• Tests/Mocks:
  • New pytests for config and behavior (test_default_scorer.py); updates to existing tests and redismock to init/cleanup defaultScorer; minor hybrid tests adjusted to expect default scorer name.

^{Written by Cursor Bugbot for commit 9110b7b. This will update automatically on new commits. Configure here.}

[redisearch-backport-pull-request]

Backport failed for 2.8, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 2.8
git worktree add -d .worktree/backport-7065-to-2.8 origin/2.8
cd .worktree/backport-7065-to-2.8
git switch --create backport-7065-to-2.8
git cherry-pick -x b61c075a870e7b4252e2caf1edcbd6c1e6162354

[redisearch-backport-pull-request]

Backport failed for 2.6, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 2.6
git worktree add -d .worktree/backport-7065-to-2.6 origin/2.6
cd .worktree/backport-7065-to-2.6
git switch --create backport-7065-to-2.6
git cherry-pick -x b61c075a870e7b4252e2caf1edcbd6c1e6162354

[redisearch-backport-pull-request]

Backport failed for 2.10, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 2.10
git worktree add -d .worktree/backport-7065-to-2.10 origin/2.10
cd .worktree/backport-7065-to-2.10
git switch --create backport-7065-to-2.10
git cherry-pick -x b61c075a870e7b4252e2caf1edcbd6c1e6162354

[redisearch-backport-pull-request]

Backport failed for 8.2, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 8.2
git worktree add -d .worktree/backport-7065-to-8.2 origin/8.2
cd .worktree/backport-7065-to-8.2
git switch --create backport-7065-to-8.2
git cherry-pick -x b61c075a870e7b4252e2caf1edcbd6c1e6162354