DataClass: List Append() not available for @dataclass member

[ubaidsk]

Example:

(lp) lpython$ cat examples/expr2.py 
from lpython import i32, dataclass

@dataclass
class A:
    x: list[i32]

def main0():
    a: A = A([1, 2, 3])
    a.x.append(4)
    print(a.x)

main0()
(lp) lpython$ python examples/expr2.py
[1, 2, 3, 4]
(lp) lpython$ lpython examples/expr2.py
semantic error: Function '' is not declared
 --> examples/expr2.py:9:5
  |
9 |     a.x.append(4)
  |     ^^^^^^^^^^^^^ 


Note: if any of the above error or warning messages are not clear or are lacking
context please report it to us (we consider that a bug that must be fixed).