feat: allow `manifest` to pull a remote policy

[jvanz]

Description

Updates the manifest command to pull the policy if it is not in the local storage.

Fix #844

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 1.33333% with 74 lines in your changes missing coverage. Please review.

Project coverage is 9.62%. Comparing base (ce7a88f) to head (71f7e58).

Files	Patch %	Lines
src/main.rs	0.00%	51 Missing :warning:
src/utils.rs	7.69%	12 Missing :warning:
src/cli.rs	0.00%	10 Missing :warning:
src/scaffold/manifest.rs	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #866 +/- ## ======================================== - Coverage 9.71% 9.62% -0.10% ======================================== Files 24 24 Lines 1801 1818 +17 ======================================== Hits 175 175 - Misses 1626 1643 +17 ``` | [Flag](https://app.codecov.io/gh/kubewarden/kwctl/pull/866/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=kubewarden) | Coverage Δ | | |---|---|---| | [unit-tests](https://app.codecov.io/gh/kubewarden/kwctl/pull/866/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=kubewarden) | `9.62% <1.33%> (-0.10%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=kubewarden#carryforward-flags-in-the-pull-request-comment) to find out more.

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[flavio]

Also, it would be nice to have some integration tests covering this new behavior