explorer_selector: Explorer Selector
In DavidBarke/shinyExplorer: Explorer and Contextmenu for Shiny apps

Use the explorer module to select a node.

explorer_selector_ui(id)

explorer_selector(
  input,
  output,
  session,
  .values,
  .root_node_r,
  .explorer_classes = list(),
  selectable_r = shiny::reactive(character()),
  addable_r = shiny::reactive(character()),
  visible_r = shiny::reactive(character()),
  .label_list = label_explorer_selector(),
  ui = c("default", "minimal"),
  mode = c("modal", "in_place"),
  action_button_fun = shiny::actionButton
)

`id`	Module id.
`input, output, session`	Called by `callModule`.
`.values`	The `.values` list.
`.root_node_r`	A `reactive` returning an object of class `ExplorerNode`. This needs not necessarily to be the root node of an object of class `ExplorerTree`.
`.explorer_classes`	A `list` of objects of class `ExplorerClass`.
`selectable_r`	A `reactive` returning a `character` vector containing labels of selectable explorer_classes.
`addable_r`	A `reactive` returning a `character` vector containing the labels of explorer classes that are addable to the explorer.
`visible_r`	A `reactive` returning a `character` vector containing the labels of explorer classes that are displayed to the user.
`.label_list`	A `list` created with `label_explorer` containing labels for all buttons used inside the explorer module.
`ui`	If `"default"`, the UI consists of an actionButton for selecting an element and an `explorer`, in which the selected element is shown. If `"minimal"`, only an actionButton showing the name of the selected element as label is shown.
`mode`	If `"modal"` a modal is opened for selecting an element. If `"in_place"` an explorer is opened in place for selecting an element.
`action_button_fun`	A `function` returning an HTML button, which is connected with shiny.

The explorer_selector module returns a list containing the following reactives:

`selected_node_r`	An object of class `ExplorerNode`, which has been selected by the user. If no node is selected, the computation is stopped by `req`.
`selected_node_or_null_r`	An object of class `ExplorerNode`, which has been selected by the user or `NULL`, if no node is selected.