Python: Support integer subscripts in the API graph

[yoff]

Recall that for

foo.f(data = d)

we can find d as moduleImport("foo").getMember("f").getKeywordParameter("data"). We will call this API path D.

We were already able to find value in

 d = {"key": value}
foo.f(d)

and

d["key"] = value
foo.f(d)

via D.getSubscript("key").

But we could not find 'value' in

 d = [value]
foo.f(d)

and

d[0] = value
foo.f(d)

at all. We can now find these via D.getIntSubscript(0).

Inspired by https://github.slack.com/archives/CPGHLR8DD/p1706707895922829