Part of #108480

Fixes #108649

Fix #109863

related to #109022

appendText should escape leading whitespace, should escape leading quote character, also remove duplicated implementations, fixes https://github.com/microsoft/vscode/issues/68983, fixes https://github.com/microsoft/vscode/issues/109040

https://github.com/microsoft/vscode/issues/109861

fixes #109456

Open to side: do not first use fileService for resolving, since item is already part of explorer model

fixes #109780

Use editor base weight when contributing peek commands, fixes https://github.com/microsoft/vscode/issues/109727#issuecomment-720986472

Fixes #109869