Deprecate bridge reload API [1/n]

Summary:
Testing the waters with an idea for unifying RN lifecycle with/without bridge.

### Motivation/Background

RN bridge is being reloaded from [several different places](https://fburl.com/codesearch/ae3zeatt). When this happens, the bridge does a bunch of things:
1. Post `RCTBridgeWillReloadNotification` (RCTSurfacePresenter listens to this and reloads)
2. Invalidate batched bridge, which does:
    a. invalidate display link
    b. post `RCTBridgeWillInvalidateModules/RCTBridgeDidInvalidateModules` (TurboModuleManager listens to this and reloads modules)
    c. clear js thread state
    d. clear some local caches
3. Set up (reload bundle and batched bridge)

In a bridgeless world, there isn't one thing which owns all these peices of infra, and can reload them.

### Plan

Use `RCTReloadCommand` to handle reloads. This light class previously only handled CMD+R. The new workflow looks like this:
1. Anything which cares about reloads can register itself as a listener. (RCTBridge, RCTSurfacePresenter, TurboModuleManager...)
2. Anything that previously called `bridge reload` now calls `RCTTriggerReloadCommandListeners`.
3. Delete old notifications

### Alternate Plan

Use yet another NSNotification. I like `RCTReloadCommand` better.

### Unknowns

Looks like we log the reason for bridge reloading [here](https://fburl.com/diffusion/lc9jj8la), do we want to save this behaviour? Does anyone look at why bridge is being reloaded cc/Rick? If so, I can add back that functionality to `RCTReloadCommand`.

It should be possible to customize the order/priority of what gets reloaded first. There may be some racy behaviour that I haven't thought about yet.

Changelog: [iOS][Deprecated] Deprecate [bridge reload] API - prefer RCTReloadCommand

Reviewed By: shergin

Differential Revision: D17869635

fbshipit-source-id: 81f39eaa2c3ce08ea1bc6f2193684c2630d81a2d

React/Base/RCTBridge.h

@@ -271,12 +271,12 @@ RCT_EXTERN void RCTEnableTurboModule(BOOL enabled);
 /**
  * Reload the bundle and reset executor & modules. Safe to call from any thread.
  */
-- (void)reload __deprecated_msg("Call reloadWithReason instead");
+- (void)reload __deprecated_msg("Use RCTReloadCommand instead");
 
 /**
  * Reload the bundle and reset executor & modules. Safe to call from any thread.
  */
-- (void)reloadWithReason:(NSString *)reason;
+- (void)reloadWithReason:(NSString *)reason __deprecated_msg("Use RCTReloadCommand instead");
 
 /**
  * Handle notifications for a fast refresh. Safe to call from any thread.
@@ -286,7 +286,7 @@ RCT_EXTERN void RCTEnableTurboModule(BOOL enabled);
 /**
  * Inform the bridge, and anything subscribing to it, that it should reload.
  */
-- (void)requestReload __deprecated_msg("Call reloadWithReason instead");
+- (void)requestReload __deprecated_msg("Use RCTReloadCommand instead");
 
 /**
  * Says whether bridge has started receiving calls from javascript.

React/Base/RCTBridge.m

@@ -294,13 +294,16 @@ - (BOOL)moduleIsInitialized:(Class)moduleClass
 }
 
 /**
- * Legacy reload, please use reloadWithReason and provide a reason for stats.
+ * DEPRECATED - please use RCTReloadCommand.
  */
 - (void)reload
 {
    [self reloadWithReason:@"Unknown from bridge"];
 }
 
+/**
+ * DEPRECATED - please use RCTReloadCommand.
+ */
 - (void)reloadWithReason:(NSString *)reason
 {
   #if RCT_ENABLE_INSPECTOR && !TARGET_OS_UIKITFORMAC
@@ -328,6 +331,9 @@ - (void)onFastRefresh
   [[NSNotificationCenter defaultCenter] postNotificationName:RCTBridgeFastRefreshNotification object:self];
 }
 
+/**
+ * DEPRECATED - please use RCTReloadCommand.
+ */
 - (void)requestReload
 {
   [self reloadWithReason:@"Requested from bridge"];

React/Base/RCTReloadCommand.h

@@ -9,12 +9,21 @@
 
 #import <React/RCTDefines.h>
 
+/**
+ * A protocol which should be conformed to in order to be notified of RN reload events. These events can be
+ * created by CMD+R or dev menu during development, or anywhere the trigger is exposed to JS.
+ * The listener must also register itself using the method below.
+ */
 @protocol RCTReloadListener
 - (void)didReceiveReloadCommand;
 @end
 
-/** Registers a weakly-held observer of the Command+R reload key command. */
+/**
+ * Registers a weakly-held observer of RN reload events.
+ */
 RCT_EXTERN void RCTRegisterReloadCommandListener(id<RCTReloadListener> listener);
 
-/** Triggers a reload for all current listeners. You shouldn't need to use this directly in most cases. */
+/**
+ * Triggers a reload for all current listeners.
+ */
 RCT_EXTERN void RCTTriggerReloadCommandListeners(void);