feat: add _GCP_PROJECT_METADATA key

[nettrino]

• [x] Followed the steps in the contributor's guide: https://crashoverride.com/docs/other/contributing#filing-the-pull-request
• [x] PR title uses semantic commit messages
• [x] Filled out the template to a useful degree
• [x] Updated CHANGELOG.md if necessary

Issue

Additional improvement over https://github.com/crashappsec/chalk/issues/298

Description

Project information is not included in the instance metadata, therefore this exposes a separate key _GCP_PROJECT_METADATA with project info, if one is found

Testing

Deploy a chalked image to GCP and check that project metadata is populated

[nettrino]

Let's add some tests as well

@miki725 we need to mock /etc/resolv.conf not sure what the best way is to go about this? I just modified a file in place to make the test pass but feel free to change as you see fit