Use the server session to get bond names instead of parsing the notebook code

[disberd]

The current way PlutoSliderServer finds bonds is by going through the parsed cell code and looking for the presence of the @bind variable: https://github.com/JuliaPluto/PlutoSliderServer.jl/blob/01f611277c962e0087767f9547b8f4b6591f0214/src/MoreAnalysis.jl#L14-L28

This unfortunately do not work for custom macros that internally create bonds.

The SliderServer already instantiate a Pluto Server session so we can directly access the bound variables that are recorded inside the PlutoRunner module. This makes it easier to track all possible bound variables without resorting to complex rules for parsing the code within the cell inputs

Discussed this approach 2 weeks ago with @fonsp.

I will fix/add test once the related Pluto PR (https://github.com/fonsp/Pluto.jl/pull/2379) is merged

[disberd]

@fonsp this is now ready for review

[disberd]

@fonsp I did just use the example you gave me on zulip :D, didn't think about timing impact but I removed HypertextLiteral and just used Markdown now which should not impact the time