Fix deadlock initializing sharedTemplates (#205)

https://leanplum.atlassian.net/browse/E2-1492

sharedTemplates was using an anti-singleton-anti-pattern. It was a dependency in its own initialization path.

Author: MaitreyaBuddha

Example/Tests/Classes/LPMessageTemplatesClassTest.m

@@ -82,6 +82,12 @@ - (void)test_dismiss_image
     XCTAssertNotNil(image);
 }
 
+-(void)test_shared_templates_creation
+{
+    // Previously, this was causing a deadlock.
+    [LPMessageTemplatesClass sharedTemplates];
+}
+
 - (void)test_popup_setup
 {
     // This stub have to be removed when start command is successfully executed.

Leanplum-SDK/Classes/Internal/LPInternalState.h

@@ -20,7 +20,7 @@
 @property(assign, nonatomic) NSUncaughtExceptionHandler *customExceptionHandler;
 @property(strong, nonatomic) LPRegisterDevice *registration;
 @property(assign, nonatomic) BOOL calledStart, hasStarted, hasStartedAndRegisteredAsDeveloper,
-startSuccessful, issuedStart, initializedMessageTemplates, stripViewControllerFromState;
+startSuccessful, issuedStart, stripViewControllerFromState;
 @property(strong, nonatomic) LPActionManager *actionManager;
 @property(strong, nonatomic) NSString *deviceId;
 @property(strong, nonatomic) NSString *appVersion;

Leanplum-SDK/Classes/Internal/LPInternalState.m

@@ -39,7 +39,6 @@ - (id)init {
         _hasStarted = NO;
         _hasStartedAndRegisteredAsDeveloper = NO;
         _startSuccessful = NO;
-        _initializedMessageTemplates = NO;
         _actionManager = nil;
         _deviceId = nil;
         _userAttributeChanges = [NSMutableArray array];

Leanplum-SDK/Classes/Internal/Leanplum.m

@@ -723,7 +723,6 @@ + (void)startWithUserId:(NSString *)userId
         [self throwError:@"Already called start."];
     }
 
-    state.initializedMessageTemplates = YES;
     [LPMessageTemplatesClass sharedTemplates];
     attributes = [self validateAttributes:attributes named:@"userAttributes" allowLists:YES];
     if (attributes != nil) {
@@ -1548,10 +1547,6 @@ + (void)defineAction:(NSString *)name ofKind:(LeanplumActionKind)kind withArgume
     }
 
     LP_TRY
-    if (![LPInternalState sharedState].initializedMessageTemplates) {
-        [LPInternalState sharedState].initializedMessageTemplates = YES;
-        [LPMessageTemplatesClass sharedTemplates];
-    }
     [[LPInternalState sharedState].actionBlocks removeObjectForKey:name];
     [[LPVarCache sharedCache] registerActionDefinition:name ofKind:kind withArguments:args andOptions:options];
     if (responder) {