Prerelease Versioning Via Deployment Count

[CodeGat]

In this PR:

• Update the logic for prerelease versions to use number of deployments + 1 instead of number of commits, which allows for rebases to model deployment repositories. This continues the convention of an ordinal number in the prerelease version, such as pr12-2 denoting the second deployment of the 12th PR.

NOTE: This means that failed deployments still take up a count. For example, if deployment 2 failed, but deployment 3 succeeded in the above example, only pr12-1 and pr12-3 would exist on the deployment target.

Important

Existing PRs that already have the existing environments counts used will not deploy successfully still

References #157
Closes #141

[harshula]

🤞