[Analytics] Events that aren't implemented properly aren't shown as errors or crashes.

Expected behavior

Events that aren't implemented properly should show in the log as an error or cause a crash in the debug builds.

@malinajirka made a comment about the rationale behind this in this PR discussion.

The comment :

We are showing a warning in the LogCat when the track event name isn't found: There is NO match for the event. Thinking about it now, we might want to consider crashing the app in debug builds as it's pretty easy to make such mistake - especially for newcomers.

Actual behavior

When you add an event to the Stat enum and the mapping with its value is not implemented here https://github.com/wordpress-mobile/WordPress-Android/blob/04cf520ef21257b9e75a94c4f47941235fd0ad47/libs/analytics/WordPressAnalytics/src/main/java/org/wordpress/android/analytics/AnalyticsTrackerNosara.java#L598

it's simply shown as a verbose warning that could be missed.

eg.

2019-08-28 19:22:18.049 25197-25197/org.wordpress.android W/WordPress-STATS: There is NO match for the event ACCOUNT_SETTINGS_CHANGE_USERNAME_FAILEDstat

Steps to reproduce the behavior

1. Add a new stat here
   https://github.com/wordpress-mobile/WordPress-Android/blob/04cf520ef21257b9e75a94c4f47941235fd0ad47/libs/analytics/WordPressAnalytics/src/main/java/org/wordpress/android/analytics/AnalyticsTracker.java#L22

2. Track the stat that's not implemented

AnalyticsTracker.track(ACCOUNT_SETTINGS_CHANGE_USERNAME_FAILED)

3. You can then filter the log using the log levelverbose flag & WordPress-STATS as the query to see the output.

Tested on [device], Android [version], WPAndroid [version]

Google Pixel 3 XL emulator, Android 9.0, WPAndroid 13.1

Start with the Stat enum in libs/analytics/WordPressAnalytics/src/main/java/org/wordpress/android/analytics/AnalyticsTracker.java and its mapping in AnalyticsTrackerNosara.java. Reproduce the missing mapping using the issue's steps and verify that an unimplemented event is reported as an error or causes a crash in debug builds instead of only producing a verbose warning.