Hover on non-function symbol in other document should show definition and documentation

[renkun-ken]

Currently, hover on non-function symbol in a document other than where it is defined does not show its definition nor documentation as it does in the document where it is defined.

For example, in languageserver code, hover on Response does not show anything while Go To Definition goes to protocol.R and hover on Response in this document the documentation is shown.

if (is.null(contents)) {
    Response$new(id)
} else {
    Response$new(
        id,
        result = list(
            contents = contents,
            range = range(
                start = document$to_lsp_position(row = range$start$row, col = range$start$col),
                end = document$to_lsp_position(row = range$end$row, col = range$end$col)
            )
        )
    )
}