Fixes <https://issues.guix.gnu.org/71979>.
* guix/modules.scm (file-name->module-name): Strip leading “.” component
from FILE.
* tests/modules.scm ("file-name->module-name")
("file-name->module-name, leading dot"): New tests.
Reported-by: Tomas Volf <~@wolfsden.cz>
Change-Id: I3d1b9f3f21448050cac4f3b1aed5f8f03758d4c9