[libc++] [docs] Migrate C++ status pages to RestructuredText (RST).
Currently, papers and issues are in separate .csv files (that is easier to update), but I can put them inline.Transforming current html tables into rst are done by the script (attached to the patch FYI but I'll remove it before committing).
I'll of course update RST files before committing to match any modifications that may happen in master branch.
This patch moves the status pages in www/ to RST format in docs/.
It also does some other minor changes: fix copyright year and broken comment end, adds substitutions for coherence (and add colors, but that can be removed easily).
It adds as well redirects from old to new status pages.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D92076