program: patch a few small conformance mismatches

[buffalojoec]

Just a few more small conformance mismatches that came from working with Firedancer's tooling.

1. Reordering lamport deduction and account realloc (on CloseLookupTable): This ordering now matches the builtin exactly.
2. Add readonly check for lookup table on CloseLookupTable: This throws a ReadonlyDataModified error at the proper callsite.
3. Add readonly lamport check for recipient on CloseLookupTable: This one is a little pedantic, but again, it provides exact backwards compatibility with error codes and throw/call sites.
4. Map sol_get_sysvar to UnsupportedSysvar: When the slot hashes data is malformed, the API for SlotHashesSysvar throws InvalidAccountData (which I think does make more sense), however the sysvar cache will throw UnsupportedSysvar for the builtin. Updates to align the codes.

[joncinque]

Looks great!