Java Formatting Import option

### Description

An option to combine imports with different Java packages together, separated from other imports.

### Use case/motivation

According to the Checkstyle I need to group Java packages: `java.*` and `javax.*` together, without blank line between them.
The import layout I need:
1. import static ...;
2. (blank line);
3. import java.\*;
4. import javax.\*;
5. (blank line);
6. import org.*;

The way I try to organize imports is specifying groups inside section "Import Layout" (Tools - Options - Editor - Formatting):
- all other imports (static);
- java., javax.;
- all other imports.

_(with checked options "Separate Groups" and "Separate Static Imports")_

After applying changes, Netbeans splits "java., javax." into two different lines, so it's not possible to combine them together.

### Related issues

_No response_

### Are you willing to submit a pull request?

No

The issue names no files, tests, or entry points. Start by locating the Java formatter's Import Layout implementation and its existing import-grouping tests. Done means allowing java.* and javax.* to remain in one group without a blank line, while preserving separate static and other-import groups.

Written by the indexing model from the issue text.