[Feature Request]: FilterState to not show shiny inputs by default

[gogonzo]

part of #48

Feature description

Please see the wireframe

1. Shiny inputs should not be visible by default. So called filter-card-summary (ui of the FilterState) should displayed - showing summarized information of the filer-state.
2. User clicks the active button in filter-card-summary to trigger change from filter-card-summary to filter-card-interactive. (Button can be a small gear icon or the card itself).
3. filter-card-interactive is rendered each time it's triggered to show (selection is based on the current state). User can change the values in filter-card-interactive and they are not propagated immediately until one clicks save. Once saved card turns back again to filter-card-summary with a new values. Thanks to updating values of the interactive selection after save only, we don't need a set_selected_reactive anymore (please see below).

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Important: Please be aware of how the FilterState$private$selected can be changed. Please see help(teal.slice:::FilterState) and go to the modyfying state, you'll see following image:

Filter states can be changed in three ways. See example FilterState$server:

• In the interactive session by directly specifying values of selected, keep_na or keep_inf using set_state method (to update all at once), or using set_selected, set_keep_na or set_keep_inf
• In a teal application by changing appropriate inputs
• Using methods set_selected_reactive, set_keep_na_reactive, set_keep_inf_reactive which serves as a programmatic API.

Important improvement would be to remove area in the dashed rectangle which will simplify this process.

[nikolas-burkoff]

If this issue involves adding a "save" button to apply the filters then: #133 and #158 should also be done with this