feat(es/config): Accept jsc.experimental.keepImportAssertions (#7995)

**Related issue:**

 - Closes #7923.

crates/swc/src/config/mod.rs

@@ -1497,7 +1497,7 @@ pub struct JscExperimental {
     #[serde(default)]
     pub plugins: Option<Vec<PluginConfig>>,
     /// If true, keeps import assertions in the output.
-    #[serde(default)]
+    #[serde(default, alias = "keepImportAssertions")]
     pub keep_import_attributes: BoolConfig<false>,
 
     #[serde(default)]

crates/swc/tests/fixture/issues-7xxx/7908/input/3/.swcrc

@@ -0,0 +1,17 @@
+{
+    "$schema": "https://json.schemastore.org/swcrc",
+    "jsc": {
+        "parser": {
+            "syntax": "typescript"
+        },
+        "target": "es2022",
+        "experimental": {
+            "keepImportAssertions": true,
+            "emitAssertForImportAttributes": true
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "isModule": true
+}

crates/swc/tests/fixture/issues-7xxx/7908/input/3/1.js

@@ -0,0 +1,3 @@
+import packageJSON from "./package.json" assert { type: "json" };
+
+console.log(packageJSON)

crates/swc/tests/fixture/issues-7xxx/7908/output/3/1.js

@@ -0,0 +1,4 @@
+import packageJSON from "./package.json" assert {
+    type: "json"
+};
+console.log(packageJSON);