Make the `--mounter` option optional. Use defaults (as with the desktop app) when it is not present

[SailReal]

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Summary

I do not want to provide the `--mounter' option all the time. We should use the same strategy here as for the desktop application, provide defaults and if the user wants to use something else, use the value of that option.

What software is involved?

• Operating System: Not relevant
• Cryptomator CLI: 0.6.0

Volume Type

None

Steps to Reproduce

1. echo "foo" | cryptomator-cli unlock /home/foo/vault/ --mountPoint=/home/foo/mounted --password:stdin

Expected Behavior

Vault gets unlocked using the default mount provider

Actual Behavior

Error: Missing required argument(s): --mounter=fully.qualified.ClassName is shown

Reproducibility

Always

Relevant Log Output

No response

Anything else?

No response