make sure VSCode shows an error message when running on a JDK <17

[martinlippert]

We need to make sure that the VSCode extension double checks the version of the JDK is runs the language server on and reports anything that is <17 to the user as a wrong setting.

See the comment here: #893 (comment)

[BoykoAlex]

@martinlippert Is this for all spring extensions or just the Spring Boot extension?

[martinlippert]

I think it makes sense to have this check for all extensions.

[BoykoAlex]

Fixed with 06dd3a8