added basic create account

- add link in to creat in users.html
- AccountController
  - add getCreateAccount
  - add postCreateAccount
- add create.html
- add AccountForm to Account Request in Mapping.kt
- add AccountForm
- add addAccount to AccountRegistryService
- add accountRegistryCreate to WebClientCalls.kt
- add UsernameDuplicateException
- add AccountRegistryException
- add HlaejaException

src/main/kotlin/ltd/hlaeja/form/AccountForm.kt

@@ -0,0 +1,9 @@
+package ltd.hlaeja.form
+
+data class AccountForm(
+    val username: String,
+    val password: CharSequence,
+    val passwordConfirm: CharSequence,
+    val role: String,
+    val enabled: Boolean = false,
+)