Rename "project" to "workspace"

[liry]

The customers get confused by using different terms for the same thing. "Project" was used historically in platform and documentation, but "workspace" term is used for years now and whole platform and docs should be fully switched soon.

Should we also rename objects/services? Or just document properly?

[liry]

First partial try: https://github.com/gooddata/gooddata-java/compare/ws