Set appropriate settings from a plugin context

[soapy1]

Description

Follow up to #1044

In order for a plugin to get settings at the right level of specificity, they must have information about the running environment and namespace. This PR:

• adds environment and namespace info into the plugin context
• updates the conda-lock plugin to use this info to get the correct conda command

Pull request checklist

• Did you test this change locally?
• Did you update the documentation (if required)?
• Did you add/update relevant tests for this change (if required)?

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[peytondmurray]

Do we even need to write to a file here?

[soapy1]

Good call out! Yes, we need to write a file because the last part of the lock_environment function is to read the output lockfile and return the contents to the user. So if the file isn't there an error is thrown about the missing file, for example, FileNotFoundError: [Errno 2] No such file or directory: '/tmp/tmpajob34th/conda-lock.yaml'. For the purpose of this test, it could be an empty file.

I think it makes sense for this to be an error. But open to change if that seems overly strict to you.

[soapy1]

Actually, this is used in another test as well. I'll refactor some so we can reuse this in all the places it's required.