Summary

Fixes #1436.

When unused imports between a package declaration and a class Javadoc/declaration are removed, the blank line that preceded the import block and the blank line that followed it were both left in place. The CLI path formats first and then fixes imports, so those stacked blanks were never re-normalized in the same pass (a second format pass fixed them).

This change:

• Coalesces adjacent unused-import deletions (RangeMap.putCoalescing)
• When a deleted import span is bordered by blank lines (or starts at the beginning of the file), absorbs one trailing blank line so package ↔ type spacing stays a single blank

Test plan

• RemoveUnusedImportsTest — includes unused import removal leaves extra blank line between package declaration and class Javadoc / declaration #1436 package + unused import + class Javadoc, multi-unused, leading-import-only, and partial-unused cases
• MainTest#unusedImportRemovalDoesNotLeaveDoubleBlankBeforeJavadoc — CLI Main.format path (format-then-fix-imports)
• mvn -pl core -am test -Dtest=RemoveUnusedImportsTest,RemoveUnusedImportsCaseLabelsTest,FormatterTest,MainTest,ImportOrdererTest → 115/115 (Temurin 21)
• Manual CLI repro: first pass is now idempotent (package + single blank + javadoc)