I know this is a bit late but in case anyone wants to bind a hotkey for this I have the following as a key binding:
{"keys":["alt+home"],"command":"run_macro_file","args":{"file":"Packages/User/macros/put-cursor-at-the-beginning-of-every-line.sublime-macro"}},
Then in that file, I have the following:
[
{"args":null,"command":"select_all"},{"args":null,"command":"split_selection_into_lines"},
{"args":{"extend":false,"to":"bol"},"command":"move_to"}
]
This makes it so when I hit ALT+HOME it puts a cursor at the beginning of every single line. I have a similar thing set for the end of a file.