feat: keyboard navigation initial implementation

[hb1998]

No description provided.

[hb1998]

stuck here

when the user clicks on a node, it navigates to that file, which moves the focus to the editor, so keyboard listener is not working unless the extension window is focussed back again.

tried this workaround
https://github.com/hb1998/react-component-tree/pull/8/files#diff-b7609b59c5c1da74fd143b1e3ffec0e40bc254cf8a7879718a4425d9ee324598R53
doesn't seem to work

[hb1998]

I was dumb enough to not notice this

react-component-tree/extension/src/SidebarProvider.ts

Line 94 in ea7164f

const editor = await vscode.window.showTextDocument(doc, { preserveFocus: true, preview: false });

making preserveFocus: true did the trick

[hb1998]

fixes #4