[Machine Outliner][RISCV] Input section aware machine outlining (#226126)

[Machine Outliner][RISCV] Input section aware machine outlining

Currently machine outliner refuses to outline from named section
functions because the callers of the outlined function could potentially be in
different input sections and since outlined function can only be in one of
the input section, this will lead to cross-section calls that breaks the
assumption around the code being all in the same section.

This PR fixes the issue by partitioning the candidates of a repeated
sequence by their parent function's input sections and emitting the outlined
function within the same section. An outlined function inherits its parents'
input section.

This input section based outlining behavior is opt-in via 
`TargetInstrInfo::supportsSectionAwareOutlining()`, which
defaults to false and has been enabled only for RISCV.

This PR also preserves the outlining behavior for x86 which allowed
outlining from named function sections however the outlined function
didn't inherit the parent function's input section.

Assisted by AI