Add provider runtime directories for python and clipboard
eval: Use scope information from provider caller in rpcrequest

When running the rpcrequest function from a ProviderCall autocommand,
temporarily switch to the caller scope.

The reason for that is because we want to trat rpcrequest calls made from
ProviderCall autocommands as if they were direct calls to the
`channel_send_call` function(ProviderCall will be used to implement old ex
commands that expect this behavior, since they were previously implemented in C)