Please add edit_readonly function similar to edit_constant #379
Description
My Pain
I'm trying to contribute a new Location widget to panel. Some of the parameters on this widget should be readonly but still be updated when the value of the corresponding Bokeh typescript model changes it value.
In order to enable this i need to set the parameters in code on the python side but this raises a TypeError.
If I change the parameters from readonly to constant then i can use the param.edit_constant contextmanager.
But the parameters should really be readonly.
Solution
Add a param.edit_readonly manager similar to the param.edit_constant manager.
Alternatively change param.edit_constant to a param.edit_constant_or_readonly manager.
Additional Context
For now I can just solve my problem in my own code by using an adjusted version of the below code.
