test(transformer): move RegExp transform conformance tests (#5536)

Rename transform conformance RegExp test fixtures folder from "esbuild-tests" to "regexp", to reflect that not all these tests are copied from ESBuild.

tasks/transform_conformance/oxc.snap.md

@@ -6,7 +6,7 @@ Passed: 21/49
 * babel-plugin-transform-nullish-coalescing-operator
 * babel-plugin-transform-optional-catch-binding
 * babel-preset-typescript
-* esbuild-tests
+* regexp
 
 
 # babel-plugin-transform-arrow-functions (1/2)

tasks/transform_conformance/src/constants.rs

@@ -57,8 +57,8 @@ pub(crate) const PLUGINS: &[&str] = &[
     // // Proposal
     // "babel-plugin-proposal-decorators",
 
-    // Tests port from esbuild
-    "esbuild-tests",
+    // RegExp tests ported from esbuild + a few additions
+    "regexp",
 ];
 
 pub(crate) const PLUGINS_NOT_SUPPORTED_YET: &[&str] = &[