move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/query/internal/genutil/pkg.go

@@ -0,0 +1,46 @@
+package genutil
+
+import (
+	"context"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+
+	"github.com/go-faster/errors"
+	"golang.org/x/tools/go/packages"
+)
+
+func loadPackages(ctx context.Context, dir, pattern string, environ []string) ([]*packages.Package, error) {
+	return packages.Load(&packages.Config{
+		Context: ctx,
+		Dir:     dir,
+		Mode: packages.NeedTypes |
+			packages.NeedTypesInfo |
+			packages.NeedTypesSizes |
+			packages.NeedSyntax |
+			packages.NeedDeps,
+		Env:  environ,
+		Fset: token.NewFileSet(),
+		ParseFile: func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
+			const mode = parser.AllErrors | parser.ParseComments
+			return parser.ParseFile(fset, filename, src, mode)
+		},
+	}, pattern)
+}
+
+// Load loads package using given pattern.
+func Load(ctx context.Context, pattern string) (*packages.Package, error) {
+	pkgs, err := loadPackages(ctx, "", pattern, os.Environ())
+	if err != nil {
+		return nil, errors.Wrap(err, "load packages")
+	}
+
+	for _, pkg := range pkgs {
+		if pkg.ID == pattern {
+			return pkg, nil
+		}
+	}
+
+	return nil, errors.Errorf("package %s not found", pattern)
+}