updated access to build.txt under mac in according to new location of the one.
(cherry picked from commit e9250f2)
(cherry picked from commit 7e40b56)
IDEA-128849 Plugin downloader can't handle HTTP redirect

Ensure that we use progress indicator
(cherry picked from commit 8864e87)
CR-IC-6500#CFR-95450
(cherry picked from commit 87850e0)
CR-IC-6500#c33030 add missed nullability annotations
(cherry picked from commit b412f2e)
Merge remote-tracking branch 'origin/139' into 139