[jspecify] configure JSpecify automatically in Eclipse and VSCode

[martinlippert]

The Eclipse distribution of the Spring Tools should have the JSpecify annotations configured automatically. Best would be to do this in a similar way than the VSCode extension does, via a popup at project import asking the user to enable and configure this or not.

The VSCode part should be enhanced for the JSpecify annotations as well.

[martinlippert]

VSCode PRs:

• Add JSpecify annotations to classpath storage eclipse-jdtls/eclipse.jdt.ls#3592
• add JSpecify annotations for null analysis redhat-developer/vscode-java#4249

[martinlippert]

The alternative first step for Eclipse could be to configure the JSpecify annotations are secondary types in the default configuration of the product, if possible.

Next step could be to ask users to enable null analysis on project import.

[martinlippert]

Both PRs for the Java support in VSCode have been merged and will most likely appear in their release coming out end of November. The default config for the Spring Tools for Eclipse distribution is in place, so I will close this one here as fixed. The additional popup to ask users to automatically enable the null analysis based on annotations in the Eclipse-based package is subject to a separate issue.