object store ApplicationDefaultCredentials auth is not working on windows

[itay-jether]

Object store default authentication (ApplicationDefaultCredentials) works with looks for a json file, which on linusx is on usually on ~/.config/gcloud/application_default_credentials.json. The path is determined by using concatentating the path of HOME environment variable with the string .config/gcloud/application_default_credentials.json

However, on windows it can be in other paths, like C:\Users\[User]\AppData\Roaming\gcloud directory, the directroy can be retrieved by gcloud info, under 'User Config Directory'.

[tustvold]

I'm afraid I don't have a windows machine on which to test this, but would welcome a PR. I presume this information must be encoded in the environment somehow

[Xuanwo]

However, on windows it can be in other paths, like C:\Users\[User]\AppData\Roaming\gcloud directory, the directroy can be retrieved by gcloud info, under 'User Config Directory'.

On windows, we should read %APPDATA%\gcloud\application_default_credentials.json instead.

[tustvold]

label_issue.py automatically added labels {'object-store'} from #5473