Handle invalid config and adjust config precedence

[f1ames]

This PR fixes #48.

As a first step I added better error handling for scenarios when Monokle: Show configuration is run. So when there is no remote config file (which is expected to be there), user will end up with similar error as below:

With change in config precedence (described below) it shouldn't happen often as in most cases local config will be used as fallback.

Then changed config precedence, so in most case when remote config cannot be fetched, it will fallback to local config - see https://github.com/kubeshop/vscode-monokle/pull/50/commits/3f96b16cf44a94cd912bd68ac2a4c93a69181be5.

And as a last step added extra comments to local config files (shown when Monokle: Show configuration is run) to point to ability of using remote configs - https://github.com/kubeshop/vscode-monokle/pull/50/commits/e8323f782ff59359726facaa20d4320ca8ef886d

Changes

• As above.

Fixes

• As above.

Checklist

• [x] tested locally
• [ ] added new dependencies
• [ ] updated the docs
• [ ] added a test