feat: Index exercises by name

BREAKING CHANGE: This changes the way you use `rustlings run` by now
requiring an abridged form of the previous filename, e.g:

`rustlings run exercises/if/if1.rs` becomes
`rustlings run if1`

tests/fixture/failure/info.toml

@@ -1,7 +1,9 @@
 [[exercises]]
+name = "compFailure"
 path = "compFailure.rs"
 mode = "compile"
 
 [[exercises]]
+name = "testFailure"
 path = "testFailure.rs"
-mode = "test"
+mode = "test"

tests/fixture/success/info.toml

@@ -1,7 +1,9 @@
 [[exercises]]
+name = "compSuccess"
 path = "compSuccess.rs"
 mode = "compile"
 
 [[exercises]]
+name = "testSuccess"
 path = "testSuccess.rs"
-mode = "test"
+mode = "test"

tests/integration_tests.rs

@@ -40,7 +40,7 @@ fn verify_all_failure() {
 fn run_single_compile_success() {
     Command::cargo_bin("rustlings")
         .unwrap()
-        .args(&["r", "compSuccess.rs"])
+        .args(&["r", "compSuccess"])
         .current_dir("tests/fixture/success/")
         .assert()
         .success();
@@ -50,7 +50,7 @@ fn run_single_compile_success() {
 fn run_single_compile_failure() {
     Command::cargo_bin("rustlings")
         .unwrap()
-        .args(&["r", "compFailure.rs"])
+        .args(&["r", "compFailure"])
         .current_dir("tests/fixture/failure/")
         .assert()
         .code(1);
@@ -60,7 +60,7 @@ fn run_single_compile_failure() {
 fn run_single_test_success() {
     Command::cargo_bin("rustlings")
         .unwrap()
-        .args(&["r", "testSuccess.rs"])
+        .args(&["r", "testSuccess"])
         .current_dir("tests/fixture/success/")
         .assert()
         .success();
@@ -70,7 +70,7 @@ fn run_single_test_success() {
 fn run_single_test_failure() {
     Command::cargo_bin("rustlings")
         .unwrap()
-        .args(&["r", "testFailure.rs"])
+        .args(&["r", "testFailure"])
         .current_dir("tests/fixture/failure/")
         .assert()
         .code(1);