Add helper to go to the middle of a line (talonhub#1424)

Adds a line command `[go] line mid` which is similar to vim's `gm` command and
moves the cursor to the middle of the line.

---------

Co-authored-by: Nicholas Riley <com-github@sabi.net>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

core/edit/edit.py

@@ -215,3 +215,11 @@ def delete_line_end():
         """Delete to end of current line"""
         actions.user.select_line_end()
         actions.edit.delete()
+
+    def line_middle():
+        """Go to the middle of the line"""
+        actions.edit.select_line()
+        half_line_length = int(len(actions.edit.selected_text()) / 2)
+        actions.edit.left()
+        for i in range(0, half_line_length):
+            actions.edit.right()

core/edit/edit.talon

@@ -185,3 +185,5 @@ redo that: edit.redo()
 # Save
 file save: edit.save()
 file save all: edit.save_all()
+
+[go] line mid: user.line_middle()