add cxx templates and improve rust template

templates/rust/.gitignore

@@ -1,2 +1,28 @@
-/.direnv/
-/target
+###### Nix Region Begin
+# Ignore build outputs from performing a nix-build or `nix build` command
+result
+result-*
+
+# Ignore automatically generated direnv output
+.direnv
+###### Nix Region End
+
+###### Rust Region Begin
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+
+# RustRover
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/
+###### Rust Region End