Add personal userspace, update keymaps (#4845)

Add personal userspace, update keymaps (#4845)

* Add kbd6x:konstantin keymap

* Prevent tap dance from sending LShift as a weak mod in KBD6X

* Move config.h and rules.mk definitions into userspace

* Add UC_WIN to UNICODE_SELECTED_MODES

* Temporarily use Bootmagic until Command is fixed

* Move common behavior from keyboards into userspace

* Update kbd6x:konstantin keymap and userspace

* Make a RCTRL layer in kbd6x:konstantin

* Make KC_ESC turn off layers

* KC_ESC turns L_FN off only if it was locked on

* Add missing record->event.pressed checks

* Move numpad toggling logic into function

* Disable Bootmagic, enable KEYBOARD_SHARED_EP with Command