Add .gitignore

Use Rust.gitignore from https://github.com/github/gitignore/blob/main/Rust.gitignore but keep Cargo.lock

Author: krisleipus

.gitignore

@@ -0,0 +1,10 @@
+# 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