Implement secure boost scheme phase 2 - enable secure xgboost via processor interface

[ZiyueXu77]

Add extensions to the vertical pipeline implemented in phase 1 to call Processor interface at proper locations to enable secure features:

• Before broadcasting g/h pairs, call interface to prepare buffer
• Communicate GHistIndexMatrix and RowSetCollection to interface for local gRPC handler in response to AllGather call

[ZiyueXu77]

Hi @trivialfis, this PR is ready for review, we have some remaining failed checks due to two issues:
3 windows checks: Cannot open include file: 'dlfcn.h' -> @nvidianz is looking into this
2 mac_os: Error: The version '3.8' with architecture 'arm64' was not found for macOS 14.4.1. -> this seems to be a recent issue impacting everyone.

[ZiyueXu77]

Hi @trivialfis, this PR is ready for review, currently we have 6 failed checks, but I think they are out of the scope of this PR, we could have more issues when triggering buildkite:

• 3 for windows, as we do not support windows at this time
• 2 for R, due to Error: Failed to get R release: Failed to get Ghostscript
• 1 for pylint, related to spark.core (is this a new thing?)

Run python tests/ci_build/lint_python.py --format=0 --type-check=0 --pylint=1
************* Module xgboost.spark.core
xgboost/spark/core.py:1450:5[7](https://github.com/dmlc/xgboost/actions/runs/9134298149/job/25119550353?pr=10124#step:7:8): E0606: Possibly using variable 'base_margin_col' before assignment (possibly-used-before-assignment)

[ZiyueXu77]

combined with #10231, close this one