build: unpin OpenAPI specs from v2.0.0-alpha.2 URL refs, use REMOTE

[petermetz]

On a high level this is a find & replace operation where the occurrences of the
first bullet point were replaced with the second bullet point:

• "$ref": "https://raw.githubusercontent.com/hyperledger/cactus/v2.0.0-alpha.2
• "$ref": "../../../../..

The firs bullet point above is called a URL reference while the second one is
called a REMOTE references (remote as in a different spec file on the file-system).

1. With this change, we unlock the release process being able to issue code that
   is working on the latest OpenAPI specifications that we are cross-referencing
   from one package to another.
2. Previously you had to manually update the references in about a hundred
   and fifty locations to make sure that the versions are bumped but after this
   change this happens automatically as the newly introduced bundling process
   and the usage of the REMOTE references instead of URL references.
3. The problem so far with the release process was that with the URL references
   we dependended on the existence of a pushed git tag for a successful release build.
   But we cannot git push the tag before having performed a successful release build,
   so this was a chicken-egg problem that had to be somehow untangled from its
   circular dependency hell and this change is what makes it happen by no longer
   depending on the git tags having been pushed to the upstream repository.

Related to, but does not yet fix: #2175

Depends on #3288

Signed-off-by: Peter Somogyvari peter.somogyvari@accenture.com

Pull Request Requirements

• Rebased onto upstream/main branch and squashed into single commit to help maintainers review it more efficient and to avoid spaghetti git commit graphs that obfuscate which commit did exactly what change, when and, why.
• Have git sign off at the end of commit message to avoid being marked red. You can add -s flag when using git commit command. You may refer to this link for more information.
• Follow the Commit Linting specification. You may refer to this link for more information.

Character Limit

• Pull Request Title and Commit Subject must not exceed 72 characters (including spaces and special characters).
• Commit Message per line must not exceed 80 characters (including spaces and special characters).

A Must Read for Beginners
For rebasing and squashing, here's a must read guide for beginners.

[github-actions]

This PR/issue depends on:

• build: add OpenAPI spec bundling, stop using URL references #3288
  By Dependent Issues (🤖). Happy coding!