Move shared utilities into backend/shared

Clears the root folder of the backend a bit to clarify which parts are entry points.

This follows from these same files being in packages/shared/ since they're
shared by multiple renderers.

Author: sebmarkbage

packages/react-devtools-shared/src/backend/console.js

@@ -32,7 +32,7 @@ import {
   supportsOwnerStacks,
   supportsNativeConsoleTasks,
 } from './fiber/DevToolsFiberComponentStack';
-import {formatOwnerStack} from './DevToolsOwnerStack';
+import {formatOwnerStack} from './shared/DevToolsOwnerStack';
 import {castBool, castBrowserTheme} from '../utils';
 
 const OVERRIDE_CONSOLE_METHODS = ['error', 'trace', 'warn'];

packages/react-devtools-shared/src/backend/fiber/DevToolsFiberComponentStack.js

@@ -24,7 +24,7 @@ import {
   describeDebugInfoFrame,
 } from '../DevToolsComponentStackFrame';
 
-import {formatOwnerStack} from '../DevToolsOwnerStack';
+import {formatOwnerStack} from '../shared/DevToolsOwnerStack';
 
 export function describeFiber(
   workTagMap: WorkTagMap,

packages/react-devtools-shared/src/backend/DevToolsComponentStackFrame.js renamed to packages/react-devtools-shared/src/backend/shared/DevToolsComponentStackFrame.js

@@ -12,7 +12,7 @@
 // while still maintaining support for multiple renderer versions
 // (which use different values for ReactTypeOfWork).
 
-import type {CurrentDispatcherRef} from './types';
+import type {CurrentDispatcherRef} from '../types';
 
 // The shared console patching code is DEV-only.
 // We can't use it since DevTools only ships production builds.