This patch changes the command interpreter sourcing logic for the REPL
init file. Instead of looking for a arbitrary file name, it standardizes
the REPL init file name to match to following scheme:
`.lldbinit-<language>-repl`
This will make the naming more homogenous and the sourcing logic future-proof.
rdar://65836048
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>