Use current file name for more "other project" future history

Use current file name for more "other project" future history

In the previous commit we added support for using the current buffer's
file name as future history for project-find-file even when switching
to another project with project-switch-project.  Make this work for
project-find-dir and project-or-external-find-file too.

* lisp/progmodes/project.el (project--find-default-from): Add.
(project-find-file, project-or-external-find-file): Use
project--find-default-from with buffer-file-name.
(project-find-dir): Use project--find-default-from with
default-directory.