Support NameLoc and CallSiteLoc for mlir::Location

The NameLoc can be used to represent a variable, node or method. The
CallSiteLoc has two fields, one represents the concrete location and another
one represents the caller's location. Multiple CallSiteLocs can be chained as
a call stack.

For example, the following call stack
```
AAA
at file1:1
at file2:135
at file3:34
```

can be formed by call0:

```
auto name = NameLoc::get("AAA");
auto file1 = FileLineColLoc::get("file1", 1);
auto file2 = FileLineColLoc::get("file2", 135);
auto file3 = FileLineColLoc::get("file3", 34);
auto call2 = CallSiteLoc::get(file2, file3);
auto call1 = CallSiteLoc::get(file1, call2);
auto call0 = CallSiteLoc::get(name, call1);
```

PiperOrigin-RevId: 226941797