suggestion: Differentiate size-thresholds levels (forbid, deny, warn)

I suggesting new way to set up various levels for thresholds, e.g.:

• forbid large_stack_frames for stack-size-threshold = 4096

• warn large_stack_frames for stack-size-threshold = 2048

  ---

• deny large_stack_arrays for array-size-threshold = 32

• warn large_stack_arrays for array-size-threshold = 16

It could be configurable in clippy.toml like this:

stack-size-threshold.forbid = 4096
# or
stack-size-threshold = { forbid = 4096, warn = 2048, ... }
# and same for array-size-threshold:
array-size-threshold.deny = 32
array-size-threshold.warn = 16

This issue describes possible improvement for clippy.toml size-thresholds configuration.
But because clippy.toml works globally for entire "project" (workspace or just crate with multiple different-purposed functions), this suggestioned changes could be highly useful in general, but not in special cases with various stack-sizes and cache-lines.
That's why I'v also create another suggestion (#15735) about a way to specify thresholds precisely for concrete item or scope.
There is also described my motivation for both suggestions.

Review the current clippy.toml settings for large_stack_frames and large_stack_arrays first. Compare this proposal with suggestion #15735, then determine the configuration syntax and precedence for forbid, deny, and warn levels. Done means an agreed, implementable design with clear behavior for each threshold level.