Some revision to Anchor package and add Anchor dashboard

[chong-he]

The Anchor dashboard is copied directly from: https://github.com/sigp/anchor/blob/stable/metrics/dashboards/anchor-dash.json

[chong-he]

This seems like required to be in the environment variables, because without this, if a user tries to change the configuration (e.g., add extra flag), they will be prompted to be required to enter this field (for new operator mode)

For import operator mode, the EXISTING_PASSWORD is already there as above

[chong-he]

I think doing this way is probably better? i.e., if a user mistakenly change the password when updating their config, that will not be effective. Because I have tested to allow changing password after the setup, and it just failed to decrypt the password and Anchor cannot start

[chong-he]

Revise the backup option to only backup the keys and not other data (logs, database) in fc2e222. Thank you discord user @gbeast for the feedback: https://discord.com/channels/747647430450741309/880470045422153758/1488751232368775199

[shane-moore]

Suggest required: true here. With required: false, a user can submit the
wizard with blank EXISTING_PASSWORD

And combined with the new [ ! -f "$PASSWORD_FILE_PATH" ] guard in entrypoint.sh, that locks in an empty password.txt and the only recovery is a full package reinstall

[chong-he]

Great feedback, revised in b01bc4f

As a side note, #7 by @3alpha also has this changed. But I change here anyway so that there is less merge conflict if any