refactor selections (#876)

* migrate selection types

* extract selection event into selections.ts

* move code-mirror selection functions into selections.ts

* move more selection logit out of code mirror and engine connection

* add selection functions pure

* tidy up naming

* write a novel about how selections work

* final comments

src/lang/std/engineConnection.ts

@@ -1,5 +1,4 @@
 import { SourceRange } from 'lang/wasm'
-import { Selections } from 'useStore'
 import { VITE_KC_API_WS_MODELING_URL, VITE_KC_CONNECTION_TIMEOUT_MS } from 'env'
 import { Models } from '@kittycad/lib'
 import { exportSave } from 'lib/exportSave'
@@ -911,30 +910,6 @@ export class EngineCommandManager {
       this.engineConnection?.send(deletCmd)
     })
   }
-  cusorsSelected(selections: {
-    otherSelections: Selections['otherSelections']
-    idBasedSelections: { type: string; id: string }[]
-  }) {
-    if (!this.engineConnection?.isReady()) {
-      console.log('engine connection isnt ready')
-      return
-    }
-    this.sendSceneCommand({
-      type: 'modeling_cmd_req',
-      cmd: {
-        type: 'select_clear',
-      },
-      cmd_id: uuidv4(),
-    })
-    this.sendSceneCommand({
-      type: 'modeling_cmd_req',
-      cmd: {
-        type: 'select_add',
-        entities: selections.idBasedSelections.map((s) => s.id),
-      },
-      cmd_id: uuidv4(),
-    })
-  }
   sendSceneCommand(command: EngineCommand): Promise<any> {
     if (this.engineConnection === undefined) {
       return Promise.resolve()