Rename `PreReleaseTag` and `PreReleaseLabel`

[asbjornu]

The existence of both PreReleaseTag and PreReleaseLabel is indeed confusing. But they are not the same thing, and are both both historical baggage from before tag was renamed to label in #3314. From the documentation:

Property	Description
PreReleaseTag	The pre-release tag is the pre-release label suffixed by the PreReleaseNumber.
PreReleaseLabel	The pre-release label.

With the following example:

{
    "PreReleaseTag": "beta.99",
    "PreReleaseLabel": "beta",
}

In this context, I'd say PreReleaseTag (the vlue beta.99) is what actually represents the "pre release label" and the current PreReleaseLabel is more like a "pre release label name", "pre release label prefix" or something similar. This seems like an omission from both the discussion in #1054 and the PR #3314.

There's not much we can do about this in v6 as it would be a breaking change, but we can consider changing this in v7.

Originally posted by @asbjornu in #4500 (reply in thread)