refactor(tvix/derivation): refactor the derivation serialization

This refactors the code to serialize a derivation. The original code
has beed moved to seperate crates for better code structure.

Change-Id: I3b1a6b134428fcbc9930c330bced8ec3610cfb4c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7733
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/derivation/src/string_escape.rs

@@ -0,0 +1,17 @@
+const STRING_ESCAPER: [(char, &str); 5] = [
+    ('\\', "\\\\"),
+    ('\n', "\\n"),
+    ('\r', "\\r"),
+    ('\t', "\\t"),
+    ('\"', "\\\""),
+];
+
+pub fn escape_string(s: &str) -> String {
+    let mut s_replaced = s.to_string();
+
+    for escape_sequence in STRING_ESCAPER {
+        s_replaced = s_replaced.replace(escape_sequence.0, escape_sequence.1);
+    }
+
+    format!("\"{}\"", s_replaced)
+}