Feature/configurable timeout

[smessmer]

Fixes #382

• cargo test has been run and passes
• documentation has been updated with relevant examples (if relevant)

[Firstyear]

Thank you @smessmer !

[micolous]

This broke the documentation build:

  Documenting webauthn-attestation-ca v0.1.0 (/home/runner/work/webauthn-rs/webauthn-rs/attestation-ca)
error: unresolved link to `webauthn_rs_core::constants::DEFAULT_AUTHENTICATOR_TIMEOUT`
   --> webauthn-rs/src/lib.rs:323:34
    |
323 |     /// If not set, defaults to [webauthn_rs_core::constants::DEFAULT_AUTHENTICATOR_TIMEOUT].
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `constants` in module `webauthn_rs_core`
    |
note: the lint level is defined here
   --> webauthn-rs/src/lib.rs:170:9
    |
170 | #![deny(warnings)]
    |         ^^^^^^^^
    = note: `#[deny(rustdoc::broken_intra_doc_links)]` implied by `#[deny(warnings)]`

error: could not document `webauthn-rs`

webauthn_rs_core::constants is not public, so you can't reference it in webauthn-rs.