internal: remove useless helpers

We generally avoid "syntax only" helper wrappers, which don't do much:
they make code easier to write, but harder to read. They also make
investigations harder, as "find_usages" needs to be invoked both for the
wrapped and unwrapped APIs

crates/mbe/src/lib.rs

@@ -66,7 +66,7 @@ impl fmt::Display for ExpandError {
 
 pub use crate::{
     syntax_bridge::{
-        ast_to_token_tree, parse_exprs_with_sep, parse_to_token_tree, syntax_node_to_token_tree,
+        parse_exprs_with_sep, parse_to_token_tree, syntax_node_to_token_tree,
         token_tree_to_syntax_node,
     },
     token_map::TokenMap,