This reverts commit 0345b40a.

null = this lookup returned nothing last time
undefined = no cached result found

Co-authored-by: Yura Beznos <yury.beznos@ocado.com>
Co-authored-by: Jamie Magee <JamieMagee@users.noreply.github.com>
Co-Authored-By: Michael Kriese <michael.kriese@visualon.de>
Co-Authored-By: Rhys Arkins <rhys@arkins.net>

* refactor(github): Remove old Github platform wrappers

* Refactor 'util/cache/run' imports

* Fix pod http client

* Fix test

* refactor(pod): Split request functions

Co-authored-by: Michael Kriese <michael.kriese@visualon.de>
Co-authored-by: Rhys Arkins <rhys@arkins.net>

This reverts commit 787e6bc4.

* chore(deps): update dependency prettier to v2

* Run prettier-fix

Co-authored-by: Renovate Bot <bot@renovateapp.com>
Co-authored-by: Jamie Magee <jamie.magee@gmail.com>

Ref #5555

A follow-up to #4246 which was insufficient.

* feat(changelog): Support Maven style tag format

* Fix lint error

Rewrites hostRules for increased flexibility. Includes renames of existing fields within a hostRule:
- `endpoint` -> `baseUrl`
- `host` -> `hostName`

Additionally, `domainName` has been added. Migration scripts should take care of these for users but it's recommended to update configs to match the new fields anyway.

Refactors hostRules to use field “hostType” instead of “platform”. hostType can include datasources like npm, maven, pypi, etc.

The code to get a list of releases was not using the RENOVATE_ENDPOINT when the npm modules it was fetching releases for had it's git repository on github enterprise.

Closes #3079