io: use io_uring for all io

There should no longer be any

- read
- write
- connect
- sendmsg
- recvmsg
- accept

calls in the codebase. Previously we were using a mix of io_uring and
these calls which had some negative effects: Since we were using the old
system calls, we had to set the file descriptors to non-blocking. But
our io_uring code did not handle EAGAIN. This lead to programs sometimes
being killed when the wayland IO was actually blocking.

Now all file descriptors are set to blocking, but io_uring makes it
non-blocking from our perspective. The one exception are evdev files
because they are read via libinput and libinput uses the old system
calls.

src/dbus/types.rs

@@ -1,8 +1,11 @@
 use {
-    crate::dbus::{
-        DbusError, DbusType, DynamicType, Formatter, Parser, TY_ARRAY, TY_BOOLEAN, TY_BYTE,
-        TY_DOUBLE, TY_INT16, TY_INT32, TY_INT64, TY_OBJECT_PATH, TY_SIGNATURE, TY_STRING,
-        TY_UINT16, TY_UINT32, TY_UINT64, TY_UNIX_FD, TY_VARIANT,
+    crate::{
+        dbus::{
+            DbusError, DbusType, DynamicType, Formatter, Parser, TY_ARRAY, TY_BOOLEAN, TY_BYTE,
+            TY_DOUBLE, TY_INT16, TY_INT32, TY_INT64, TY_OBJECT_PATH, TY_SIGNATURE, TY_STRING,
+            TY_UINT16, TY_UINT32, TY_UINT64, TY_UNIX_FD, TY_VARIANT,
+        },
+        utils::buf::DynamicBuf,
     },
     std::{borrow::Cow, ops::Deref, rc::Rc},
     uapi::{OwnedFd, Packed, Pod},
@@ -458,7 +461,7 @@ impl<'a> Variant<'a> {
         }
     }
 
-    pub fn write_signature(&self, w: &mut Vec<u8>) {
+    pub fn write_signature(&self, w: &mut DynamicBuf) {
         let c = match self {
             Variant::U8(..) => TY_BYTE,
             Variant::Bool(..) => TY_BOOLEAN,