Refactor: Add request body for create, and changed migrate elem body.

src/main/kotlin/com/wafflestudio/csereal/core/admissions/api/req/AdmissionMigrateElem.kt

@@ -0,0 +1,11 @@
+package com.wafflestudio.csereal.core.admissions.api.req
+
+import org.jetbrains.annotations.NotNull
+
+data class AdmissionMigrateElem(
+    @field:NotNull val name: String?,
+    val mainType: String,
+    val postType: String,
+    val language: String,
+    @field:NotNull val description: String?
+)

src/main/kotlin/com/wafflestudio/csereal/core/admissions/api/req/AdmissionReqBody.kt

@@ -0,0 +1,9 @@
+package com.wafflestudio.csereal.core.admissions.api.req
+
+import org.jetbrains.annotations.NotNull
+
+data class AdmissionReqBody(
+    @field:NotNull val name: String?,
+    val language: String = "ko",
+    @field:NotNull val description: String?
+)