Raises a deprecation warning issue per-dependency. Uses logic that if latest version is deprecated then the package is deprecated.

Closes #1592

Adds logic to detect presence of “deprecated” field in latest version. First step towards #1592

This reverts commit b46a95a9.

This reverts commit 04e0ca1f.

Refactors credentials/token handling to rely less on env variables and instead use an endpoints middleware for credentials handling.

First step towards #2105

Renames "date" and "time" values from datasources to instead be "releaseTimestamp".

Adds a wrapper to all datasources to provide a generic purl-based interface.

Closes #1764 

This PR follows up and fixes #1968

The previous PR didn't behave correctly as it was expecting Github Enterprise to ALWAYS been configured and that the github.com token was available in the `GITHUB_COM_TOKEN` env variable.
But for non GHE project `GITHUB_COM_TOKEN` is not defined and github.com token is available at the `GITHUB_TOKEN` env variable instead.

This updated PR fix this issue and avoid further problems by prioritising `github.com` over GHE.
Now the code is NOOP if no `GITHUB_ENDPOINT` is configured.

If it's configured, instead, now the codes assumes that, by DEFAULT, a dependency is hosted on `github.com` so it removes `GITHUB_ENDPOINT` and use `GITHUB_COM_TOKEN` as Github token immediately.
They are restored only if needed, when a dependency is hosted on the provided GithubEnterprise.

This reverts commit 7fcbb47b.

This reverts commit 080d9451.

Closes #1988

This reverts commit f2fb2e6b.

as nexus hosted npm repository does not automatically 'extracts' any value from the published versions we have to manually pick the repository and namepage fields from the latest version if not already defined in the reponse root