Escape the remote system query

[veduco]

#157
https://github.com/vmstan/gravity-sync/discussions/158

When the script gs-core.sh is executed or sourced, the $RH_EXEC command is actually parsed on the local machine, and then used against the remote machine. This can lead to checking for a non-existent container name on the remote server, instead of properly parsing the remote system's configuration.

Example:
On load,

RH_EXEC="sudo ${ROCKER_BIN} exec $(sudo ${ROCKER_BIN} ps -qf name=${ROCKER_CON}) pihole"

becomes sudo /usr/bin/docker exec 0ce8b1d5571d pihole, which is then used in an SSH command against the remote host, yielding:

[i] Inverting Tachyon Pulses
[e] Updating Remote FTLDNS ConfigurationError: No such container: 0ce8b1d5571d
[✗] Updating Remote FTLDNS Configuration

because, of course, the container ID doesn't exist on the remote host.

The fix is to escape the nested command execution within gs-core.sh, like so:

--- gs-core.sh.orig     2021-02-17 17:43:53.732747200 -0700
+++ gs-core.sh  2021-02-17 17:43:34.690296100 -0700
@@ -102,7 +102,7 @@ function ph_type {
         RH_EXEC="${RIHOLE_BIN}"
     elif [ "$RH_IN_TYPE" == "docker" ]
     then
-        RH_EXEC="sudo ${ROCKER_BIN} exec $(sudo ${ROCKER_BIN} ps -qf name=${ROCKER_CON}) pihole"
+        RH_EXEC="sudo ${ROCKER_BIN} exec \$(sudo ${ROCKER_BIN} ps -qf name=${ROCKER_CON}) pihole"
     elif [ "$RH_IN_TYPE" == "podman" ]
     then