Configuration cache & compatibility checks

[badsyntax]

This is both a bug report and a feature request.

• A recent change to add --no-configuration-cache is throwing an error in Gradle versions < 6.6. Refs Disable gradle config cache #274 & Incompatible with configuration cache #273 & It works, but slow #217 (comment). See also: https://blog.gradle.org/introducing-configuration-caching
• Some people are experiencing slow performance in older projects, see: It works, but slow #217

What we need to do is:

• Determine the minimum supported version of Gradle & Spotless Grade Plugin and gather this information from vscode-gradle
• Show a message to the user informing them of any incompatibility

This will require a change in vscode-gradle to surface build information (Gradle version and dependency versions). vscode-gradle already has this information, there's just no public API to access it.

cc @nedtwigg