[lldb][docs] Update .htaccess to redirect from old SB API documentation to new one

This is mostly SEO so that the new API can take over the old API when people
search for the different SB* classes. Sadly epydoc decided to throw in a -class
prefix behind all the class file names, so we can't just overwrite the old files
with the newly generated ones.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D94900