[ImportVerilog] add unpacked array concatenation

[chenbo-again]

This PR is aimed to provide unpacked array concatenation.

// unpacked array concatenation
string s[] = { "hello", "sad", "world" };
// string concatenation
string = { "hello", "sad", "world" };

these two operation do not act the same way, and the result of concat is depends on the Lhs.

close #8173

[chenbo-again]

This PR import UnpackedArrayConcatOp operation, This Operation is very similar to array_create operation, but can use unpacked array as operands.