[WIP] Remove global random engine.

[trivialfis]

Move the random engine into the context.

todos:

• Seed the rng based on the number of boosted rounds.
• Test serialization with sampling.
• Test with related issues.

Related:

• Hist training with checkpointing is non-deterministic based on subsample #10324
• boosters that should be training identically are not #6711

[trivialfis]

Note:

• Creating a column sampler runs the random engine to get an initial seed.
• The failing test gtest is caused by the difference in the serialized rng state instead of the output model.