Make 1Password CLI package configurable and fix pkgs._1password warning

[LukeChannings]

The _1password package was renamed to _1password-cli in nixpkgs.

Using the _1password package prints the following:

evaluation warning: _1password has been renamed to _1password-cli to better follow upstream name usage

This PR is similar to #498, but they missed the invocation on line 11 so it still prints the warning.

Changes

• Add a cliPackage option, which defaults to _1password-cli. Users may want to use a custom version of the 1Password CLI without using an overlay - this provides that option.
• The evaluation message is no longer printed

[github-actions]

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