fix #62112 - merge overlapping delete operations

Use an overload instead of a conditional type to generate a compile error when using `vscode.previewHtml` command

Conditional types were breaking on our build machine

Supports cases like https://github.com/Microsoft/typescript-styled-plugin/issues/41

Requires TS 3.2

#60565.

* dispose submenu after use

* dispose in the native case as well

fixes #60488

Fixes #43076