The interference checking in lowering bases some of its checks on
GenTree::gtFlags. This is conservative since it includes effect flags of
operands. For LIR this does not really make sense and ends up being
conservative.

This PR replaces the relevant uses of gtFlags with a new
GenTree::OperEffects() that computes the relevant effect flags for the
node, excluding operands. We already know how to recompute effect flags
other than GTF_GLOB_REF and GTF_ORDER_SIDEEFF. This PR adds functions
for these as well (the GTF_GLOB_REF version
GenTree::OperRequiresGlobRefFlag is courtesy of @SingleAccretion).

For GTF_ORDER_SIDEEFF we add a GenTree::OperSupportsOrderingSideEffect
which captures explicitly (and conservatively) the current cases where
we are setting the flag, and only allows these cases to support the
flag. Setting the flag for other cases may result in the flag being
removed or ignored.

Fix dotnet#92699