manifest: remove some ManifestProject properties

These are just duplicating functionality already present in the parent
class. The abspath property has to stay because, unlike Project,
ManifestProject might have a self._path set to None (... which,
looking at it again, is yet another reason it's not sensible to treat
it like a Project).

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

src/west/manifest.py

@@ -783,19 +783,6 @@ class ManifestProject(Project):
         # Extension commands.
         self.west_commands = _west_commands_list(west_commands)
 
-    @property
-    def path(self):
-        return self._path
-
-    @path.setter
-    def path(self, path):
-        self._path = path
-
-        # Invalidate the absolute path attributes. They'll get
-        # computed again next time they're accessed.
-        self._abspath = None
-        self._posixpath = None
-
     @property
     def abspath(self):
         if self._abspath is None and self.topdir and self.path:
@@ -803,12 +790,6 @@ class ManifestProject(Project):
                                                           self.path))
         return self._abspath
 
-    @property
-    def posixpath(self):
-        if self._posixpath is None and self.abspath:
-            self._posixpath = PurePath(self.abspath).as_posix()
-        return self._posixpath
-
     def as_dict(self):
         '''Return a representation of this object as a dict, as it would be
         parsed from an equivalent YAML manifest.'''