Move app/src (mostly) to flipper-ui-core/src

Summary:
This diff moves all UI code from app/src to app/flipper-ui-core. That is now slightly too much (e.g. node deps are not removed yet), but from here it should be easier to move things out again, as I don't want this diff to be open for too long to avoid too much merge conflicts.

* But at least flipper-ui-core is Electron free :)
* Killed all cross module imports as well, as they where now even more in the way
* Some unit test needed some changes, most not too big (but emotion hashes got renumbered in the snapshots, feel free to ignore that)
* Found some files that were actually meaningless (tsconfig in plugins, WatchTools files, that start generating compile errors, removed those

Follow up work:
* make flipper-ui-core configurable, and wire up flipper-server-core in Electron instead of here
* remove node deps (aigoncharov)
* figure out correct place to load GKs, plugins, make intern requests etc., and move to the correct module
* clean up deps

Reviewed By: aigoncharov

Differential Revision: D32427722

fbshipit-source-id: 14fe92e1ceb15b9dcf7bece367c8ab92df927a70

desktop/flipper-ui-core/src/reducers/usageTracking.tsx

@@ -0,0 +1,108 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {produce} from 'immer';
+import {Actions} from './';
+import {SelectionInfo} from '../utils/info';
+import {getRenderHostInstance} from '../RenderHost';
+
+export type TrackingEvent =
+  | {
+      type: 'WINDOW_FOCUS_CHANGE';
+      time: number;
+      isFocused: boolean;
+    }
+  | {
+      type: 'SELECTION_CHANGED';
+      selectionKey: string | null;
+      selection: SelectionInfo | null;
+      time: number;
+    }
+  | {type: 'TIMELINE_START'; time: number; isFocused: boolean};
+
+export type State = {
+  timeline: TrackingEvent[];
+};
+const INITAL_STATE: () => State = () => ({
+  timeline: [
+    {
+      type: 'TIMELINE_START',
+      time: Date.now(),
+      isFocused: getRenderHostInstance().hasFocus(),
+    },
+  ],
+});
+
+export type Action =
+  | {
+      type: 'windowIsFocused';
+      payload: {isFocused: boolean; time: number};
+    }
+  | {type: 'CLEAR_TIMELINE'; payload: {time: number; isFocused: boolean}}
+  | {
+      type: 'SELECTION_CHANGED';
+      payload: {selection: SelectionInfo; time: number};
+    };
+
+export default function reducer(
+  state: State = INITAL_STATE(),
+  action: Actions,
+): State {
+  if (action.type === 'CLEAR_TIMELINE') {
+    return {
+      ...state,
+      timeline: [
+        {
+          type: 'TIMELINE_START',
+          time: action.payload.time,
+          isFocused: action.payload.isFocused,
+        },
+      ],
+    };
+  } else if (action.type === 'windowIsFocused') {
+    return produce(state, (draft) => {
+      draft.timeline.push({
+        type: 'WINDOW_FOCUS_CHANGE',
+        time: action.payload.time,
+        isFocused: action.payload.isFocused,
+      });
+    });
+  } else if (action.type === 'SELECTION_CHANGED') {
+    const {selection, time} = action.payload;
+    return produce(state, (draft) => {
+      draft.timeline.push({
+        type: 'SELECTION_CHANGED',
+        time,
+        selectionKey: selection?.plugin ? JSON.stringify(selection) : null,
+        selection,
+      });
+    });
+  }
+  return state;
+}
+
+export function clearTimeline(time: number): Action {
+  return {
+    type: 'CLEAR_TIMELINE',
+    payload: {
+      time,
+      isFocused: getRenderHostInstance().hasFocus(),
+    },
+  };
+}
+
+export function selectionChanged(payload: {
+  selection: SelectionInfo;
+  time: number;
+}): Action {
+  return {
+    type: 'SELECTION_CHANGED',
+    payload,
+  };
+}