Updating Helm settings and adding new bindings

Added helm-mode to `use-package` idle timer to load when idle instead of just defer.

"SPC s" Bindings ("s" prefix signifies showing buffer data)
- sy = yank / kill ring
- sm = mark ring
- sr = registers

"SPC f" Bindings ("f" prefix signifies file activies)
- fh = helm-find-files

"SPC F1" is `helm-apropos`
Indeed `<SPC> b s` does work but there is no "Helm completion enabled" message in `*Messages*`. Wait for a few seconds and it will appears. By duplicating `(helm-mode +1)` in `:prog` the first `<SPC> b s` shows the message.

I don't know exactly what this message is for, but there is a difference between the 2 behaviors and I prefere the behaviors to be consistent.