Make rng in TestEnv deterministic and seedable (#461)

* 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.

* Add testing for TestCustomization

* Change assert comparison to assert_eq

* Separate tests

* Move 3 pure constants to new file

* Return Vec<String> for rp_ids()

* Make rng in TestEnv deterministic and seedable

* Move seed method to TestRng256

* Change some constant name in comments to snake case

* Move seed rng of env to the start

* Fix unused warning

* Make rng in TestEnv deterministic and seedable

* Move seed method to TestRng256

* Move seed rng of env to the start

* Fix unused warning

* Seed rng in all fuzz targets

* Fix error introduced when merging

Co-authored-by: Julien Cretin <cretin@google.com>

Cargo.toml

@@ -23,12 +23,13 @@ subtle = { version = "2.2", default-features = false, features = ["nightly"] }
 serde_json = { version = "=1.0.69", default-features = false, features = ["alloc"] }
 embedded-time = "0.12.1"
 arbitrary = { version = "0.4.7", features = ["derive"], optional = true }
+rand = { version = "0.8.4", optional = true }
 
 [features]
 debug_allocations = ["lang_items/debug_allocations"]
 debug_ctap = ["libtock_drivers/debug_ctap"]
 panic_console = ["lang_items/panic_console"]
-std = ["crypto/std", "lang_items/std", "persistent_store/std"]
+std = ["crypto/std", "lang_items/std", "persistent_store/std", "rand"]
 verbose = ["debug_ctap", "libtock_drivers/verbose_usb"]
 with_ctap1 = ["crypto/with_ctap1"]
 with_nfc = ["libtock_drivers/with_nfc"]