Bug: Dict methods do not work on a `Const dict`

[kmr-srbh]

Trying to use dict methods on Const dict result in a Internal Compiler Error.

get()

d: Const[dict[str, i32]] = {"a": 1, "b": 2, "c": 3}
print(d.get("a"))

(base) saurabh-kumar@Awadh:~/Projects/System/lpython$ ./src/bin/lpython ./examples/example.py
Internal Compiler Error: Unhandled exception
Traceback (most recent call last):
.
.
.
AssertFailed: is_a<T>(*f)

keys()

d: Const[dict[str, i32]] = {"a": 1, "b": 2, "c": 3}
print(d.keys())

(base) saurabh-kumar@Awadh:~/Projects/System/lpython$ ./src/bin/lpython ./examples/example.py
Internal Compiler Error: Unhandled exception
Traceback (most recent call last):
.
.
.
AssertFailed: is_a<T>(*f)

The error is the same for other available methods.