Modifying debugger to return the same breakpoints in 'debugInfo' response as 'setBreakpoints'

[vaishnavi17]

In this PR, I make changes to debugger.py so that the breakpoints returned in a debugInfo response match the breakpoints returned in the most recent setBreakpoints request.

Bug context:
When a user clicks on a gutter to add/remove a breakpoint, a setBreakpoints request is sent. The UI changes according to the response of the setBreakpoints request, which gives a list of the breakpoints that were actually added. debugInfo is used to populate the UI breakpoints when a notebook is refreshed. So, it is important that the debugInfo and setBreakpoints information aligns.

Let's say we try to add a breakpoint at a commented out line (say line 2). debugpy will infer that that line is not a runnable piece of code, so it will add a breakpoint to the line of code before that (say line 1), and the setBreakpoints response will consist of a breakpoint at line 1. However, the debugInfo request is implemented by ipykernel, and the list of breakpoints for that is maintained by just recording the breakpoints that were sent in the setBreakpoints request. So, a debugInfo request would contain the information that there is a breakpoint at line 2. This causes confusing jumping behavior when the debugInfo request gets called, like on refresh.

In the video, the breakpoint jumps from line 1 to line 2 when the page is refreshed. Then, if I try to add a breakpoint at line 1, the breakpoint at line 2 disappears (because the setBreakpoints response contains the correct info, which is that there is no breakpoint at line 2).

inconsistent-breakpoints.mov

Fix:
I fix this by modifying the setBreakpoints request handler indebugger.py to record the response of the setBreakpoints request as the information for the debugInfo request.

[blink1073]

Thank you! I'll release this early next week.