feat: add command base

[gabor-boros]

Reason for the change

Creating a base for porting management commands of the 2.4.x driver.

Description

This PR creates the base and structure for management commands:

• dump
• export
• import
• index_rebuild
• repl
• restore

Code examples

# Calling the dump command
$ rethinkdb-dump
# ... or ...
$ rethinkdb dump

# Calling the export command
$ rethinkdb-export
# ... or ...
$ rethinkdb export

# Calling the import command
$ rethinkdb-import
# ... or ...
$ rethinkdb import

# Calling the index_rebuild command
$ rethinkdb-index_rebuild
# ... or ...
$ rethinkdb index_rebuild

# Calling the repl command
$ rethinkdb-repl
# ... or ...
$ rethinkdb repl

# Calling the restore command
$ rethinkdb-restore
# ... or ...
$ rethinkdb restore

Checklist

• I have read and agreed to the RethinkDB Contributor License Agreement

References
N/A