Fix parsing expressions to evaluate with spaces and optional args (MI)

Summary:
When extracting options for long options (starting with `--`), the use of
`MIUtilString::SplitConsiderQuotes` to split all the arguments was being
conditioned on the option type to be expected. This was wrong as this caused
other options to be parsed incorrectly since it was not taking into account the
presence of quotes.

Patch by Ed Munoz <edmunoz@microsoft.com>

Reviewers: edmunoz, ki.stfu

Subscribers: ki.stfu, lldb-commits

Projects: #lldb

Differential Revision: https://reviews.llvm.org/D24202

llvm-svn: 282135