Issue title: can @biesbjerg/ngx-translate-extract be installed globally?
 Issue body: Hi 

can @biesbjerg/ngx-translate-extract be installed globally?

 Comments: 
 Comment 0: Sure, that should work
 Comment 1: I tried it and it’s not working... keeps asking for dependencies to be installed
 Comment 2: Oh, I think I know what's up. 

Global install is not supported because it can't reliably parse source code, since it depends on the version of typescript and angular compiler used in the project

More details here:
https://github.com/biesbjerg/ngx-translate-extract/issues/173#issuecomment-609665560
 Comment 3: how can I use ngx-translate-extract without it being installed in scripts?

 Comment 4: It is not a feature I am going to support for the reasons I linked to. Sorry!
{'source': 'GithubIssues', 'repo_name_with_owner': 'biesbjerg/ngx-translate-extract', 'issue_id': 629225820, 'repo_stars': 508.0}