Zero-diff part of "Use SSA-based ComputeRange"

[EgorBo]

Extracted from #112824 for simpler code review

[dotnet-policy-service]

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

[EgorBo]

@jakobbotsch @AndyAyersMS @dotnet/jit-contrib PTAL, zero-diff change. Just preparations for using RangeCheck in assertprop (in #112824):

1. Hid all maps under lazy-init getters (these maps are cleaned on every GetRange call, so the state is not shareable between phases).
2. RangeCheck becomes a singleton instance - this helps to reduce TP impact and allocations when it's called from Assertprop
3. Removed verbose SSA validation - it's quite ad-hoc and messy, also, it's an additional state that I had to reset between phases. RangeCheck used to be the last phase to use SSA, but it's not the case today so if we need it, we have to come up with some generic SSA validation and use it everywhere.
4. Propagated block into various optAssertionProp_* that I'll need.

CI failures are unrelated.