Organize imports enhancement

Currently "Organize imports" will do three things:

• Add missing imports
• Remove all unused imports
• Sort existing imports

And there are serveral requests about feature "Organize imports":

Organize import without sorting:

• https://github.com/redhat-developer/vscode-java/issues/1575#issue-677597353
• https://github.com/redhat-developer/vscode-java/issues/1575#issuecomment-879667855

Organize imports (and other code actions) in multiple files:

• https://github.com/redhat-developer/vscode-java/issues/1107
• https://github.com/redhat-developer/vscode-java/issues/2282
• https://github.com/microsoft/vscode-java-pack/issues/1085

We can find rooms to improve. Although we have configuration java.completion.importOrder, it's not such visible and it's hard to "hardcode" a package list for some users. In this way, we can have serveral points to improve:

• Add "Remove all unused imports" quickfix for related warnings https://github.com/eclipse/eclipse.jdt.ls/pull/2280
  • it just remove all unused imports, will not affect existing valid imports
• Add "Add all missing imports" quickfix for related errors https://github.com/eclipse/eclipse.jdt.ls/pull/2292
  • it just add all missing imports, will not affect(sort) existing valid imports
• Support "Add all missing import" when pasting https://github.com/redhat-developer/vscode-java/pull/2795
  • related API: https://github.com/microsoft/vscode/issues/30066
• Support code actions (and formatting maybe) in folder level

Es sind keine Dateien oder Tests genannt. Beginne mit der Durchsicht der verknüpften Issues und Pull Requests und verfolge anschließend den bestehenden Organize imports-Ablauf und dessen Code Actions für einzelne Dateien; als erledigt gilt die Unterstützung von Code Actions auf Ordnerebene, ohne das bestehende Verhalten zum Hinzufügen, Entfernen und Sortieren zu beeinträchtigen.