Move three dependent customizations into new file

* default_min_pin_length(_rp_ids) and max_rp_ids_length

* Did some backing store tricks to make the list configurable in
  TestCustomization.

src/env/test/customization.rs

@@ -0,0 +1,82 @@
+use std::slice::from_raw_parts;
+
+use crate::api::customization::{Customization, CustomizationImpl};
+use crate::ctap::data_formats::CredentialProtectionPolicy;
+
+pub struct TestCustomization {
+    pub default_min_pin_length: u8,
+    default_min_pin_length_rp_ids_backing_store: Vec<String>,
+    default_min_pin_length_rp_ids: Vec<*const str>,
+    pub default_cred_protect: Option<CredentialProtectionPolicy>,
+    pub max_msg_size: usize,
+    pub max_rp_ids_length: usize,
+}
+
+impl TestCustomization {
+    pub fn set_default_min_pin_length_rp_ids(&mut self, rp_ids: Vec<String>) {
+        self.default_min_pin_length_rp_ids_backing_store = rp_ids;
+        self.default_min_pin_length_rp_ids = self
+            .default_min_pin_length_rp_ids_backing_store
+            .iter()
+            .map(|s| s.as_ref() as *const str)
+            .collect::<Vec<_>>();
+    }
+}
+
+impl Customization for TestCustomization {
+    fn default_cred_protect(&self) -> Option<CredentialProtectionPolicy> {
+        self.default_cred_protect
+    }
+
+    fn default_min_pin_length(&self) -> u8 {
+        self.default_min_pin_length
+    }
+
+    fn default_min_pin_length_rp_ids(&self) -> &[&str] {
+        let length = self.default_min_pin_length_rp_ids.len();
+        let rp_ids = self.default_min_pin_length_rp_ids.as_ptr() as *const &str;
+        unsafe { from_raw_parts(rp_ids, length) }
+    }
+
+    fn max_msg_size(&self) -> usize {
+        self.max_msg_size
+    }
+
+    fn max_rp_ids_length(&self) -> usize {
+        self.max_rp_ids_length
+    }
+}
+
+impl From<CustomizationImpl> for TestCustomization {
+    fn from(c: CustomizationImpl) -> Self {
+        let CustomizationImpl {
+            default_min_pin_length,
+            default_min_pin_length_rp_ids,
+            default_cred_protect,
+            max_msg_size,
+            max_rp_ids_length,
+        } = c;
+
+        let default_min_pin_length_rp_ids_backing_store = default_min_pin_length_rp_ids
+            .iter()
+            .map(|s| (*s).to_owned())
+            .collect::<Vec<_>>();
+
+        let mut ret = Self {
+            default_min_pin_length,
+            default_min_pin_length_rp_ids_backing_store,
+            default_min_pin_length_rp_ids: vec![],
+            default_cred_protect,
+            max_msg_size,
+            max_rp_ids_length,
+        };
+
+        ret.default_min_pin_length_rp_ids = ret
+            .default_min_pin_length_rp_ids_backing_store
+            .iter()
+            .map(|s| s.as_ref() as *const str)
+            .collect::<Vec<_>>();
+
+        ret
+    }
+}