Prefer explicit construction to coercion in record initialization

While we support initializing records via coercion from an expression
list, e.g.,

    local x: X = [$x1=1, $x2=2];

this can sometimes obscure the code to readers, e.g., when assigning to
value declared and typed elsewhere. The language runtime has a similar
overhead since instead of just constructing a known type it needs to
check at runtime that the coercion from the expression list is valid;
this can be slower than just writing the readible code in the first
place, see #4559.

With this patch we use explicit construction, e.g.,

    local x = X($x1=1, $x2=2);

scripts/base/frameworks/tunnels/main.zeek

@@ -92,7 +92,7 @@ export {
 
 event zeek_init() &priority=5
 	{
-	Log::create_stream(Tunnel::LOG, [$columns=Info, $path="tunnel", $policy=log_policy]);
+	Log::create_stream(Tunnel::LOG, Log::Stream($columns=Info, $path="tunnel", $policy=log_policy));
 	}
 
 function register_all(ecv: EncapsulatingConnVector)