Deprecate using cli version already deprecated build-doc', build-test', and `make'

[rjbou]

No description provided.

[dra27]

This doesn't appear to be working correctly:

$ ./opam install bitmasks --build-doc
opam: build-doc was removed in version 2.1 of the opam CLI, but version 2.1 has been requested. Use --with-doc instead or set OPAMCLI environment variable to 2.0.

[dra27]

Ouch, there's a more serious problem as well (not necessarily introduced with this PR, but in CLI versioning): OPAMBUILDDOC=true ./opam install bitmasks silently "works" to select the with-doc dependencies of bitmasks.

[rjbou]

There is no handling of environment variables in cli versioning, only cli.

[dra27]

This is an oversight/error for options which have been removed - it shouldn't be that --build-doc is banned but you can quietly persuade opam to do it with an "old" environment variable!

[rjbou]

I think at that time, it was removed from doc, but kept handled to not break scripts. We can set up a new guidelines for environment variables deprecation.

[rjbou]

Queued, to rebase on cli versioning environment variables edition

[dra27]

LGTM!