app, shiny-ui-base: datafiles output: Replace handsontable with DT

shiny-ui-base.R(render_dt,simple_style_dt): New functions.

(update_gui): Updated.

(rf_get_inp_datafiles): Removed.

(datafiles-edit): New observer.

(datafiles_b, mzml_from_inp): Update observers.

(output$datafiles): Updated.

app.Rmd(datafiles): Updated output.