* Introduce Customization trait
* Introduce Customization trait including the customization accessors
that control various behaviors.
* Expose Customization through a getter API in Env, and make the code
that directly access the constants currently switch to accessing the
customizations via Env.
* TockEnv's customization getter implementation directly returns the
reference of the global DEFAULT_CUSTOMIZATION constant, so the
constant values are still inlined and dead code won't be compiled.
* We'll add the customizations from global constants to the struct
one-by-one, only MAX_MSG_SIZE in this commit.
* Small fixes
* Fix deploy script
* put is_valid under std gate
* Add crate arbitrary as ctap's optional dependency, when feature "fuzz"
is activated.
* Derive Arbitrary for all the necessary types in order to generate the
concrete types from random bytes.
* Add a fuzz target that transforms the input to valid format for
MakeCredential.
We don't need to build a production key without persistent storage. Tests and
fuzzing continue to use the std feature to use the RAM implementation (that does
sanity checks).
