LYN-2723: Fixes issues with bad project or engine paths (#369)

* Setup NativeUIRequests as an AZ::Interface.  Adds a NativeUISystemComponent to AzFramework Application.

* Renames NativeUISystemComponent (class) to NativeUISystem, since it's no longer a Component.

* Minor update to SettingsRegistryInterface::Remove doc-comments for accuracy.

* Fixes to make an early fatal shutdown of Editor occur without crash.

* LYN-2723: Updates startup to handle errors: engine root is empty, no valid project.json found (mismatched engine name), or bad project path (launch project picker dialog).

* LYN-2723: Minor formatting/spelling edits.

* LYN-2723: Moves ParseCommandLine from ComponentApplication to SettingsRegistryMergeUtils so it can be used in more places.

* Misc fixes. 'wait_for_connect' setting wasn't being properly applied to AP connection settings. Fix infinite loop in CCmdLine::Next.

* LYN-2723: Addresses review feedback.

* LYN-2723: Reverts some changes that caused a unit test to fail.

* LYN-2723: Reverts one more change that was unnecessary.

Code/Framework/AzFramework/AzFramework/Asset/AssetSystemComponentHelper.cpp

@@ -220,7 +220,7 @@ namespace AzFramework
             {
                 // Read the wait for connection boolean from the Settings Registry
                 AZ::s64 waitForConnect64{};
-                if (!AZ::SettingsRegistryMergeUtils::PlatformGet(*settingsRegistry, waitForConnect64, AZ::SettingsRegistryMergeUtils::BootstrapSettingsRootKey, AzFramework::AssetSystem::WaitForConnect))
+                if (AZ::SettingsRegistryMergeUtils::PlatformGet(*settingsRegistry, waitForConnect64, AZ::SettingsRegistryMergeUtils::BootstrapSettingsRootKey, AzFramework::AssetSystem::WaitForConnect))
                 {
                     outputConnectionSettings.m_waitForConnect = waitForConnect64 != 0;
                 }