gh-104584: Allow unspecialized instructions in superblocks (#106497)

This adds several of unspecialized opcodes to superblocks:

TO_BOOL, BINARY_SUBSCR, STORE_SUBSCR,
UNPACK_SEQUENCE, LOAD_GLOBAL, LOAD_ATTR,
COMPARE_OP, BINARY_OP.

While we may not want that eventually, for now this helps finding bugs.

There is a rudimentary test checking for UNPACK_SEQUENCE.

Once we're ready to undo this, that would be simple:
just replace the call to variable_used_unspecialized
with a call to variable_used (as shown in a comment).
Or add individual opcdes to FORBIDDEN_NAMES_IN_UOPS.