Python: Add copy of extractor tests

These get to live next to the existing library and query tests, and are
run as part of both the Python 2 and Python 3 language tests.

python/ql/test/extractor-tests/ast/test.py

@@ -0,0 +1,143 @@
+
+@deco1
+@deco2()
+@deco3.attr1.attr2
+class C(Base):
+
+    def __init__(self):
+        pass
+
+@deco4.attr()
+def f():
+    pass
+
+def f(pos0, pos1, *args, **kwargs):
+    pass
+
+def simple_stmts():
+    pass
+    foo() ; del x; pass
+    if thing:
+        for a in b:
+            pass
+    #Expressions
+    tmp = (
+        yield 3,
+        name,
+        attr.attrname,
+        a + b,
+        3 & 4,
+        3.0 * 4,
+        a.b.c.d,
+        a().b[c],
+        lambda x: x+1,
+        p or q and r ^ s,
+        a < b > c in 5,
+        { 1 : y for z in x for y in z},
+        { (1, y) for z in x for y in z},
+        [ y**2 for y in z ],
+        [],
+        {},
+        (),
+        (1,),
+    )
+    foo(1)
+    foo(a=1)
+    foo(1,2,*t)
+    foo(1,a=1,*t)
+    foo(1,a=1,*t,**d)
+    f(**d)
+
+def compound_stmts():
+    if cond:
+        return x
+    else:
+        raise y
+    while True:
+        if cond:
+            break
+        else:
+            continue
+    for x in y:
+        pass
+    with a as b, c as d:
+        body
+    try:
+        t1
+    except:
+        e1
+    try:
+        t2
+    except Exception:
+        e2
+    try:
+        t3
+    except Exception as ex:
+        e3
+    try:
+        t4
+    finally:
+        f4
+    try:
+        t5
+    except Exception as ex:
+        e5
+    finally:
+        f5
+    try:
+        t6
+    finally:
+        try:
+            t7
+        finally:
+            f7
+
+#Unusual classdef
+class WhyUseParens():
+    pass
+
+#Annotations
+x: 1
+x: y
+x: {y[a][b]:z-q}
+x: f(1, d=3, *t)
+
+
+#f-strings with format specifier
+f'result: {value:0.2f}'
+f'result: {value:{width}.{precision}}'
+
+
+f"Too {'many' if alen > elen else 'few'} parameters for {cls};"
+    #f" actual {alen}, expected {elen}"
+
+#Backticks
+`backticks`
+`why, are, we, still, supporting, this in 2019`
+
+
+def numeric_literals():
+    # Various corner cases for numeric literals
+    tmp = (
+        0b00010101011111111111L,
+        1_1,
+        0b1_1,
+        0x1_1,
+        0b_010,
+        0x_010,
+        0_0,
+        009.,
+        009e005,
+        00123,
+        0o77777777777L,
+        0777777777777L,
+        0o1_1,
+        0o_010,
+        1_2_3.4_5_6e7_8_9,
+        0_0234j
+    )
+
+#Grammar ambiguity in extractor version 5.4
+print(f'{"foo"}')
+print(f"{"bar"}")
+