Add `--password-file` to `crypto jwe encrypt`

[eest]

Name of feature:

Add --password-file to crypto jwe encrypt

Pain or issue this feature alleviates:

Makes it possible to run the command without prompts for input if e.g. running it from a script to modify the password of a user as described in https://smallstep.com/docs/step-ca/provisioners/#changing-a-jwk-provisioner-password. The flag also matches the already available flag for the decrypt command. Also the usage string for the decrypt command has been updated to mention decryption. This fix basically mirrors how things are done in decrypt.go.

Why is this important to the project (if not answered above):

Helpful for scripting with the step client.

Is there documentation on how to use this feature? If so, where?

The flag includes a usage string.

In what environments or workflows is this feature supported?

Any using step cli.

In what environments or workflows is this feature explicitly NOT supported (if any)?

N/A

Supporting links/other PRs/issues:

💔Thank you!

[CLAassistant]

All committers have signed the CLA.

[eest]

@dopey is there something missing here for this to be accepted?