Support modal remapping

[k0kubun]

Close #89

Example

default_mode: insert
keymap:
  - mode: insert
    remap:
      Esc: { set_mode: normal }
  - mode: normal
    remap:
      i: { set_mode: insert }
      h: Left
      j: Down
      k: Up
      l: Right

[cipherlogs]

this is a terrific feature if it can be added, I have tested the code but it is not working at all

here are my bindings

keymap:
  # - name: Global
  - mode: insert
    remap:
      j:
        remap:
          j: {set_mode: normal}
          k: Esc
          l: C-space
        timeout_millis: 100

  - mode: normal
    remap:
      i: {set_mode: insert}
      h: Left
      l: Right
      k: Up
      j: Down

to trigger normal mode I have to go jj but it doesn't work
also I have tried to add nested remaps inside normal mode it doesn't work at all

I hope this feature doesn't die. if we can do a true vim like modal remapping that would be amazing.

[k0kubun]

Could you make it a separate issue so that I can remember it when I work on open issues?