Support data breakpoints

[ydmykr]

As is shown in the VSCode document,

If a debugger supports data breakpoints, they can be set from the context menu in the VARIABLES view. The Break on Value Change/Read/Access commands will add a data breakpoint that is hit when the value of the underlying variable changes/is read/is accessed. Data breakpoints are shown with a red hexagon in the BREAKPOINTS section.

Can Python extension support this function? I think C++ support this function by clicking Break When Value Changes button while Python didn't.

I think this would be a very convenient feature for Python users.

[gramster]

Dup of #1291