Display & configure memory page map.

[tomusdrw]

As seen at https://www.youtube.com/watch?v=lF7Di5Qwut4&t=2767s it isn't clear how is page map affecting the execution of the code in PVM debugger.

I believe it would be good to:

1. Display access type of the page in a memory tooltip (readable / writeable / non-accessible). We may even have different background colors indicate page accessibility.
2. View current page map (it may change during execution because of sbrk)
3. Edit the page map (currently it's only possible to either load JSON file or SPI to have that configured)
4. Store page map in the URL (to allow easy sharing). The ?program parameter might even be SPI program.