Installing directly from rb file no longer supported by
homebrew without HOMEBREW_DEVELOPER set after https://github.com/Homebrew/brew/pull/20414
was merged.
Create local tap for install to avoid need for homebrew developer mode.
Task-number: QTQAINFRA-7344
Change-Id: Id59af01875b16d1757b1dba36c2ba04bf973c212
Reviewed-by: Simo Fält <simo.falt@qt.io>