Provide a way to ignore dependencies when performing dependencyUpdates

[jrhee17]

Often, we use ./gradlew dependencyUpdates to check dependencies which needs updates before each release.

Oftentimes, we go through the tedious process of checking each dependency and seeing if we can upgrade it.

However, for some dependencies this may be a false-positive due to:

• Some dependencies are used to test for compatibility, so we use older versions intentionally
• We support different versions of certain dependencies
• Some dependencies shouldn't be upgraded due to license issues

For this, I propose that we add a tag section which explicitly either

• ignores a certain dependency
• Overrides the most recent dependency

By doing so, hopefully we can also implement automatic version upgrades