[vscode] Support InputBox#valueSelection

[rschnekenbu]

see https://code.visualstudio.com/api/references/vscode-api#InputBox

• valueSelection: readonly [number, number]
  Selection range in the input value. Defined as tuple of two number where the first is the inclusive start index and the second the exclusive end index. When undefined the whole pre-filled value will be selected, when empty (start equals end) only the cursor will be set, otherwise the defined range will be selected.
  This property does not get updated when the user types or makes a selection, but it can be updated by the extension.

[jonah-iden]

Hi, i would try working on this issue