test: use canonical nested library imports

lib/encoding/base32/base32_test.ww

@@ -1,6 +1,6 @@
 package base32_test;
 
-import base32;
+import encoding.base32;
 
 fn putstr(s: str, into: []u8, off: i32) i32 = {
 	let i: i32 = 0;

lib/encoding/base64/base64_test.ww

@@ -8,7 +8,7 @@
 
 package base64_test;
 
-import base64;
+import encoding.base64;
 import bytes;
 import errors;
 import io;