Column breakpoint

[cosminadrianpopescu]

This PR adds the possibility to also set the column when toggling or setting a breakpoing.

For example, given this code:

const arr = [{name: 'Name 1', id: 1}, {name: 'Name 2', id: 2}];
console.log(arr.map(x => x.id));

If I go on the second line and I call lua require('dap').toggle_breakpoint(), this would set the breakpoint before logging. This means that the program would stop only once, before the console log, without giving me the possibility to stop and to debug also what happens inside the mapping.

This PR adds the toggle_breakpoint_column, with the same parameters as toggle_breakpoint.

So, for example, I could go with the cursor on the x from x.id (line 2, column 26) and call lua require('dap').toggle_breakpoint_column(). This would set the breakpoint inside the arr.map. This means that it would stop for each value of the array, and I could debug each value of the array.