[proposal] @veramo/cli should use a default config location

**Is your feature request related to a problem? Please describe.**

Right now, if you want to use a `veramo` command in the terminal, you have to point to a config file or run the command from a folder that has a valid agent.yml file.

**Describe the solution you'd like**

It would be much more useful if some commands that don't require too much overhead could be run from anywhere.
(I'm thinking of resolving a DID or verifying a signature)

**Describe alternatives you've considered**

an alternative would be to use an alias:
```bash
veramo config create --filename ~/.veramo/agent.yml
echo "alias vrm=\"veramo --config $HOME/.veramo/agent.yml"\" >> ~/.bashrc
source ~/.bashrc
```
and then use `vrm` for ephemeral commands