Make sure repository license can be correctly detected

[wiegandm]

What:

Individual files describing the license status of this module have been renamed to ensure correct license detection by GitHub.

Why:

Currently, GitHub is unable to determine the license of this repository since the file COPYING does not contain the text of a license, but rather details on the licensing of individual source code file.

This leads to the license being displayed as Unknown, GPL-2.0 licenses found in the GitHub web interface and as:

    "licenseInfo": {
      "key": "other",
      "name": "Other",
      "nickname": ""
    },

when retrieved via the API.

Having the license detectable by GitHub makes it easier for both developers and automated processes to assess the licensing.

How:

As GitHub seems to not do license detection on branches, I used the licensee ruby gem to validate the file.
Before:

COPYING:
  Content hash:  1761efd6e733621f80c7303f70ab83eede5641e1
  License:       NOASSERTION
  Closest non-matching licenses:
    Vim similarity:           11.39%
    OFL-1.1 similarity:       7.53%
    MulanPSL-2.0 similarity:  6.90%

After:

COPYING:
  Content hash:  2bad07668a4461ecadbfc380652eba2a0db5112c
  Confidence:    99.83%
  Matcher:       Licensee::Matchers::Dice
  License:       GPL-2.0
  Closest non-matching licenses:
    GPL-2.0 similarity:  99.83%
    MPL-2.0 similarity:  44.39%
    EPL-2.0 similarity:  38.26%

Checklist:

• Tests N/A
• PR merge commit message adjusted