fix(go): resolve method names from field_identifier in method_declaration

[singh-aashutosh]

Summary

Go methods were often missing from the knowledge graph or stored under the wrong name (for example int64, string, error) because _get_name() did not match how tree-sitter-go models method names.

Root cause

For method_declaration, the method name is a field_identifier child, not an identifier. The generic loop only matches identifier, type_identifier, and similar. That leads to:

• Methods without a result type: no matching name → the method is skipped entirely.
• Methods with a named result type (e.g. int64): the first type_identifier after the parameter lists is the return type, which was incorrectly used as the function name.

Change

In _get_name(), add a Go-specific branch for method_declaration that returns the field_identifier text, placed before the generic child loop (same ordering idea as the existing C/C++ handling so return types are not mistaken for names).

Verification

• Parse a small file with func (s *T) Foo() {} and func (s *T) Bar() int64 { return 0 }; both should emit Function nodes named Foo and Bar, not int64.
• Parse a large service.go with many receiver methods; Function count should match expectations and bogus int64 / string / error “functions” from return types should disappear.