tool-cache._getOsVersion should improve to detect RHEL compatible Linux distro version.

Describe the enhancement

tool-cache._getOsVersion() had been using /etc/lsb-release to detect Linux OS versions, but recently, it was improved to use /etc/os-release from systemd : #594

But it used VERSION_ID only, and it does not process Linux distro information.

• Here are contents of /etc/os-release from various Linux Distros.
  • https://gist.github.com/ganadist/5dec6462ad052b7d572cde743c0b98b5
• RHEL and its compatible distros have compatible ABI if they have same major version, but their VERSION_ID are different.
  • CentOS : 8
  • RockyLinux : 8.7

IMHO, the purpose of tool-cache._getOsVersion() is to distinguish the ABI of the OS.
So, I propose to improve it as follows.

• Return PLATFORM_ID first if it is available from /etc/os-release

  • RHEL based Linux distros provides PLATFORM_ID which OS is compatible.
    • RHEL 8.x, CentOS 8.x, and Rocky Linux 8.x have same PLATFORM_ID=platform:el8

• Return old behavior (VERSION_ID from /etc/os-release) if PLATFORM_ID is not available.

  • This can keep compatiblity with current behavior.

Code Snippet
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Additional information
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Start by locating tool-cache._getOsVersion() and the existing /etc/os-release parsing. Check how VERSION_ID is currently selected, then verify the result for RHEL-compatible distributions with and without PLATFORM_ID. Done means PLATFORM_ID is preferred when present and VERSION_ID remains the fallback.