Simplify a little, and avoid duplicate commands

Simplify a little, and avoid duplicate commands

* lisp/progmodes/project.el:
(project--transient-p) Remove, not needed.
(project-current): Move project-find based on the directory here.
(project--remove-from-project-list): Only write if the list changed.
(project-find-project): Rename to project-prompt-project-dir.
Simply return the directory selected by the user.
(project-switch-project-find-file): Remove.
(project-switch-project-dired): Rename to project-dired and make
it follow the convention of existing projec tcommands.
(project-switch-project-eshell): Ditto.
(project-switch-project): Instead of passing the project instance
to the command, just bind default-directory.