assigning literal arrays to ARRAY[..] OF STRING in the implementation-body is broken

[mhasel]

Describe the bug
When trying to assign a literal string-array (e.g. ['a', 'b', 'c'] to an ARRAY[0..2] OF STRING, inkwell will panic with the following message:

thread '<unnamed>' panicked at /home/michael/.cargo/registry/src/index.crates.io-6f17d22bba15001f/inkwell-0.2.0/src/values/enums.rs:278:13:
Found PointerValue(PointerValue { ptr_value: Value { name: "utf08_literal_0", address: 0x7672c800d5f0, is_const: true, is_null: false, is_undef: false, llvm_value: "@utf08_literal_0 = private unnamed_addr constant [2 x i8] c\"g\\00\"", llvm_type: "[2 x i8]*" } }) but expected the ArrayValue variant

To Reproduce
Steps to reproduce the behavior:

Compile the following example:

FUNCTION main 
VAR
    arr: ARRAY[0..2] OF STRING;
    arr2: ARRAY[0..2] OF DINT;
END_VAR
    arr := ['a', 'b', 'c'];
    arr2 := [1, 2, 3];
END_FUNCTION

Expected behavior
The string-array should be overwritten with the values in the literal array.

Additional context
The code works fine for the ARRAY[..] OF DINT.