Implements Hunt basic create and get, and adds field validation to controllers

src/main/kotlin/net/halfbinary/scavengerhuntapi/model/request/HunterSignupRequest.kt

@@ -1,7 +1,14 @@
 package net.halfbinary.scavengerhuntapi.model.request
 
+import jakarta.validation.constraints.Email
+import jakarta.validation.constraints.NotBlank
+
 data class HunterSignupRequest(
+    @field:Email(message = "Must be a valid email address")
+    @field:NotBlank(message = "Email must not be blank")
     val email: String,
+    @field:NotBlank(message = "Name cannot be blank")
     val name: String,
+    @field:NotBlank(message = "Password cannot be blank")
     val password: String
 )