Add an options to reset page objects

[krystian8207]

The list of objects:

• reactive values (see: https://appsilon.com/how-to-safely-remove-a-dynamic-shiny-module/)
• output values (output$name <- NULL see #69)
• observers (see: https://appsilon.com/how-to-safely-remove-a-dynamic-shiny-module/)

[dokato]

@krystian8207 is this completed?

[krystian8207]

@dokato Yes, the current implementation doesn't require this feature anymore.