By splitting dvc.cli into a module, we'll be able to share cli-related
utilities, split parser-related stuffs into smaller parts, improve
reusability and improve API for command extensions in the future.
Currently we don't handle bad name well:
```
(dvc-3.8.3) ➜ dvc git:(config-bug) ✗ dvc config section
ERROR: unexpected error - not enough values to unpack (expected 2, got 1)
```
With this PR, we check name to conform to either `remote.name.option` or
`section.option`, so we'll give a more friendly:
```
(dvc-3.8.3) ➜ dvc git:(config-bug) ✗ dvc config section
ERROR: argument name: name argument should look like remote.name.option or section.option
usage: dvc config [-h] [--global | --system | --local] [-q | -v] [-u] [-l] [name] [value]
Get or set config options.
Documentation: <https://man.dvc.org/config>
positional arguments:
name Option name (remote.name.option or section.option).
value Option value.
optional arguments:
-h, --help show this help message and exit
--global Use global config.
--system Use system config.
--local Use local config.
-q, --quiet Be quiet.
-v, --verbose Be verbose.
-u, --unset Unset option.
-l, --list List all defined config values.
```
skshetry
Saugat Pachhai (सौगात)
Ruslan Kuprieiev
Batuhan Taskaya