Remove dynamic types

Do not use dynamic types anymore. The reason is that it's difficult:

- to maintain a shared type database over a network.
- the extra overhead when translating between processes and for
  maintaining the translation tables.
- race conditions in translating in RT-threads, this is a problem
  because we want to make event streams.

We now have simple enums with types and extension points for all
types. This is also nicer to use in general.
We don't need the mapper anymore or pass strings around as types.
There is a parallel type info system to get more info about ids and
enums and their hierarchy. It can also be used for debugging.

src/gst/gstpipewirepool.c

@@ -71,7 +71,6 @@ void gst_pipewire_pool_wrap_buffer (GstPipeWirePool *pool, struct pw_buffer *b)
   GstBuffer *buf;
   uint32_t i;
   GstPipeWirePoolData *data;
-  struct pw_type *t = pool->t;
 
   GST_LOG_OBJECT (pool, "wrap buffer");
 
@@ -84,19 +83,19 @@ void gst_pipewire_pool_wrap_buffer (GstPipeWirePool *pool, struct pw_buffer *b)
     GstMemory *gmem = NULL;
 
     GST_LOG_OBJECT (pool, "wrap buffer %d %d", d->mapoffset, d->maxsize);
-    if (d->type == t->data.MemFd) {
+    if (d->type == SPA_DATA_MemFd) {
       gmem = gst_fd_allocator_alloc (pool->fd_allocator, dup (d->fd),
                 d->mapoffset + d->maxsize, GST_FD_MEMORY_FLAG_NONE);
       gst_memory_resize (gmem, d->mapoffset, d->maxsize);
       data->offset = d->mapoffset;
     }
-    else if(d->type == t->data.DmaBuf) {
+    else if(d->type == SPA_DATA_DmaBuf) {
       gmem = gst_dmabuf_allocator_alloc (pool->dmabuf_allocator, dup (d->fd),
                 d->mapoffset + d->maxsize);
       gst_memory_resize (gmem, d->mapoffset, d->maxsize);
       data->offset = d->mapoffset;
     }
-    else if (d->type == t->data.MemPtr) {
+    else if (d->type == SPA_DATA_MemPtr) {
       gmem = gst_memory_new_wrapped (0, d->data, d->maxsize, 0,
                                      d->maxsize, NULL, NULL);
       data->offset = 0;
@@ -107,7 +106,7 @@ void gst_pipewire_pool_wrap_buffer (GstPipeWirePool *pool, struct pw_buffer *b)
 
   data->pool = gst_object_ref (pool);
   data->owner = NULL;
-  data->header = spa_buffer_find_meta_data (b->buffer, t->meta.Header, sizeof(*data->header));
+  data->header = spa_buffer_find_meta_data (b->buffer, SPA_META_Header, sizeof(*data->header));
   data->flags = GST_BUFFER_FLAGS (buf);
   data->b = b;
   data->buf = buf;