Undocumented crucible-related saw-script commands

[brianhuffman]

For lots of crucible-related saw-script commands, the in-REPL documentation is just "TODO". For example:

sawscript> :? crucible_llvm_verify
Description
-----------

    crucible_llvm_verify : String -> [CrucibleMethodSpec] -> CrucibleSetup () -> Bool -> ProofScript SatResult -> TopLevel CrucibleMethodSpec

TODO

At the very least, we need to describe what each function argument is.

[brianhuffman]

Here are the remaining undocumented REPL commands as of revision 73c81fc (July 27), along with the offenders courtesy of git blame:

• extract_crucible_llvm (@robdockins)
• crucible_fresh_expanded_val (@glguy)
• crucible_llvm_unsafe_assume_spec (@glguy)