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/gen/_template/struct_slice.tmpl

@@ -0,0 +1,23 @@
+{{- /*gotype: go.mau.fi/mautrix-telegram/pkg/gotd/gen.structDef*/ -}}
+{{ define "struct_slice" }}{{ $f := . }}
+{{ template "slice" $f }}
+
+{{ range $field := sortableFields ($f.Fields) }}
+    {{ template "slice_sort_by" concat ($f) ($field) }}
+{{ end }}
+{{ range $field := mapCollectableFields ($f.Fields) }}
+// FillMap fills constructors to given map.
+func (s {{ template "slice_name" $f }}) Fill{{ template "map_collector_name" $field }}Map(to map[{{ $field.Type }}]{{ $f.Name }} ) {
+    for _, value := range s {
+        to[value.Get{{ $field.Name }}()] = value
+    }
+}
+
+// ToMap collects constructors to map.
+func (s {{ template "slice_name" $f }}) To{{ template "map_collector_name" $field }}Map() map[{{ $field.Type }}]{{ $f.Name }} {
+    r := make(map[{{ $field.Type }}]{{ $f.Name }}, len(s))
+    s.Fill{{ template "map_collector_name" $field }}Map(r)
+    return r
+}
+{{ end }}
+{{ end }}