Add support for item access from Const data-structures (#2579)

* Add support for accessing items from data-structures within `Const`

* Update type checking logic for `Const dict`

Co-authored-by: Thirumalai Shaktivel <[email protected]>

* Minor formatting change

Co-authored-by: Thirumalai Shaktivel <[email protected]>

* Handle negative indices for `const list` and minor formatting changes

* Add tests

* Update test references

* Heavily simplify handling `const`

* Tests: Add compile time test

* Remove calls to `type_get_past_const()`

* Tests: Update test references

* Remove extra newline

Co-authored-by: Shaikh Ubaid <[email protected]>

* Delete tests/reference/asr-test_const_access-82a9a24.json

* Delete tests/reference/asr-test_const_access-82a9a24.stdout

* Delete tests/reference/asr-test_const_str_access-59ff543.stderr

* Delete tests/reference/asr-test_const_tuple_access-0d4c6df.json

* Delete tests/reference/asr-test_const_tuple_access-0d4c6df.stderr

* Delete tests/reference/asr-test_const_str_access-59ff543.json

* Formatting changes

* Tests: Add test to CMakeLists and update error references

* Update asr_to_llvm.cpp

* Undo formatting changes

* Undo formatting changes

* Revert throwing error for `Const` annotated tuples and strings

* Tests: Remove error references

* Remove redundant visitor

* Undo moving `index`

---------

Co-authored-by: Thirumalai Shaktivel <[email protected]>
Co-authored-by: Shaikh Ubaid <[email protected]>

integration_tests/CMakeLists.txt

@@ -556,6 +556,7 @@ RUN(NAME test_list_compare   LABELS cpython llvm llvm_jit)
 RUN(NAME test_list_concat    LABELS cpython llvm llvm_jit c NOFAST)
 RUN(NAME test_list_reserve   LABELS cpython llvm llvm_jit)
 RUN(NAME test_const_list     LABELS cpython llvm llvm_jit)
+RUN(NAME test_const_access     LABELS cpython llvm llvm_jit)
 RUN(NAME test_tuple_01       LABELS cpython llvm llvm_jit c)
 RUN(NAME test_tuple_02       LABELS cpython llvm llvm_jit c NOFAST)
 RUN(NAME test_tuple_03       LABELS cpython llvm llvm_jit c)

integration_tests/test_const_access.py

@@ -0,0 +1,9 @@
+from lpython import i32, Const
+
+CONST_LIST: Const[list[i32]] = [1, 2, 3, 4, 5]
+CONST_DICTIONARY: Const[dict[str, i32]] = {"a": 1, "b": 2, "c": 3}
+
+assert CONST_LIST[0] == 1
+assert CONST_LIST[-2] == 4
+
+assert CONST_DICTIONARY["a"] == 1