studio: Cache credentials

[daavoo]

do we need to store these tokens stored somewhere in "${XDG_DATA_HOME:-$HOME/.local/share}/dvclive/credentials.toml"? To be able to cache them and not care about setting them all time. from @mvshmakov

[daavoo]

Assigning low priority for now because there are workarounds like handling in .env files https://pypi.org/project/python-dotenv/ and this can cause a discrepancy between Local and Remote setup (in remote setup, env vars make more sense in order to be combined with GitHub/GitLab secrets)

[mvshmakov]

Also, there is a direnv for (non-)nix environments which also solves this problem to some extent. Though, say, gh-cli and aws-cli cache their creds in a way defined in this issue.

[daavoo]

Will not be addressed by DVCLive