Pull request generator - Bitbucket cloud support

[Jamess-Lucass]

Summary

Same enhancement as #10695 with a slightly different proposal following ideas from #11150 and the existing implementation for bitbucket-server referenced in the docs here

What change you think needs making.

Motivation

A lot of users, including myself, use the cloud version of bitbucket and would benefit from being able to utilize the pull request generator feature provided by Argo CD.

Proposal

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: myapps
spec:
  generators:
    - pullRequest:
        bitbucket:
          # Workspace name where the repoistory is stored under. Required.
          owner: myproject
          # Repository slug. Required.
          repo: myrepository
          # URL of the Bitbucket Cloud API. (optional) Will default to 'https://api.bitbucket.org/2.0'.
          api: https://api.bitbucket.org/2.0
          # Credentials for Basic authentication. Required for private repositories.
          basicAuth:
            # The username to authenticate with
            username: myuser
            # Reference to a Secret containing the password or personal access token.
            passwordRef:
              secretName: mypassword
              key: password
        # Labels are not supported by Bitbucket Cloud, so filtering by label is not possible.
        # Filter PRs using the source branch name. (optional)
        filters:
          - branchMatch: ".*-argocd"
  template:
  # ...

Named bitbucket to keep aligned to how the scmProvider is named in #11150

• owner (required) could be named several different things, possibly workspace to follow the naming in Bitbucket Cloud REST API docs

• api (optional) is the base url for where the pull requests are queried from - In most cases this will remain https://api.bitbucket.org/2.0 and if the api is not set or left blank, it will default back to https://api.bitbucket.org/2.0

• basicAuth (optional) is to support authenticating to private bitbucket cloud repositories