Add support for BellSoft API downloads

[tresf]

Adds support for BellSoft API authentication which can download a JDK that's been build specifically for a BellSoft customer (such as QZ Industries, LLC).

# Fetch a copy of the JDK from BellSoft's support portal
jlink.api.enabled=false
jlink.api.url=https://api.bell-sw.com/v1/liberica/releases
# jlink.api.token=
# jlink.api.exact=false <-- false: use latest found version; true: match jlink.java.version exactly

TODO:

• 🚫 REDACTED: Determine how to provide these values to ant from our Company Branded portal
  Edit:: We'll just keep this as a local-only tool.

[Vzor-]

Looks good