chore: clean up and reorganize the repo (#134)

* chore: move FieldVerticalSeparator into src

* chore: move FieldColoudSlider into src

* chore: move FieldMatrix into src

* chore: move FieldNote into src

* chore: move FieldNumber into src

* chore: move FieldVariable into src/fields

* chore: move FieldVariableGetter into src/fields

* chore: import fields from their new paths

* chore: fix imports in FieldVariable

* chore: format FieldNumber

* chore: fix imports in FieldNumber

* chore: move event classes into events directory

* chore: fix event imports

* chore: fix importing events

* chore: move css.js into src

* chore: move colours.js into src

* chore: format files referencing colours.js

* chore: fix imports of colours.js

* chore: move scratch_blocks_utils.js into src

* chore: move field_textinput_removable.js into src

* chore: only import core Blockly

* chore: move block definitions into src/blocks

* chore: delete unused block files

* chore: fix block imports

* chore: delete the unused horizontal block definitions

* chore: delete old build/import tooling

* chore: format files

Author: gonfunko