Add author filtering to commit view

This commit introduces a new feature to the commit view, allowing users
to filter commits based on the author's name or email address. Similar
to the existing path filtering functionality, accessible through <c-s>,
this feature allows users to filter the commit history by the currently
selected commit's author if the commit view is focused, or by typing in
the author's name or email address.

This feature adds an entry to the filtering menu, to provide users with
a familiar and intuitive experience

pkg/gui/gui.go

@@ -386,7 +386,7 @@ func (gui *Gui) resetState(startArgs appTypes.StartArgs) types.Context {
 			Authors:               map[string]*models.Author{},
 		},
 		Modes: &types.Modes{
-			Filtering:        filtering.New(startArgs.FilterPath),
+			Filtering:        filtering.New(startArgs.FilterPath, ""),
 			CherryPicking:    cherrypicking.New(),
 			Diffing:          diffing.New(),
 			MarkedBaseCommit: marked_base_commit.New(),