fix: remove attestation conveyance preference check in attestation statement implementations

[tanguilp]

Fixes: #51

[makmn1]

I ran this against the official test suite and the good news is that there are no regressions from the changes here compared to the current version (0.7). That said, I did run into a few issues which you might run into when you get a chance to run the tests:

• I had to remove the exception block that was added here for the tests to run since the test server triggers the exception to be raised.
• The last version for wax_api_rest (0.5) causes 20+ test failures due to changes made to invalidate_challenge:

[error] #PID<0.2327.0> running WaxFidoTestSuiteServerWeb.Endpoint (connection #PID<0.448.0>, stream id 269) terminated
Server: localhost:4000 (http)                                                                                                                                    
Request: POST /attestation/result                                                                                                                                
** (exit) an exception was raised:                                                                                                                               
    ** (UndefinedFunctionError) function WaxFidoTestSuiteServerWeb.UserKeyCallbackImpl.invalidate_challenge/1 is undefined or private                            
        (wax_fido_test_suite_server 0.1.0) 

• When running with wax_api_rest version 0.4 against wax 0.7 / the changes here, there are only four failures, with the last one being related to the metadata service tests (which the test suite instructions say to skip). Failures:

Server-ServerAuthenticatorAttestationResponse-Resp-1 Test server processing ServerAuthenticatorAttestationResponse structure
F-15 Send ServerAuthenticatorAttestationResponse with authenticatorData.flags.uv set to false when userVerification is set to 'required' and check that server returns an error‣
Error: Promise succeded when expected to fail! 
    at file:///C:/Users/makmn/AppData/Local/Programs/fido-conformance-tools-electron/resources/app.asar/app/js/utils.js:1162:39
	
Server-ServerAuthenticatorAttestationResponse-Resp-9 Test server processing "tpm" attestation
P-1 Send a valid ServerAuthenticatorAttestationResponse with "tpm" attestation for SHA-256, and check that server succeeds‣
Error: Server responed with error. The errorMessage is: Failed to verify attestation of type tpm (reason: invalid_certificate)
    at eval (eval at compileCode (js/sandbox.js:25:26), <anonymous>:4528:19)
	
P-2 Send a valid ServerAuthenticatorAttestationResponse with "tpm" attestation for SHA-1, and check that server succeeds‣
Error: Server responed with error. The errorMessage is: Failed to verify attestation of type tpm (reason: invalid_certificate)
    at eval (eval at compileCode (js/sandbox.js:25:26), <anonymous>:4528:19)
	
Server-MDS3 Test server support for Metadata Service 3
P-1 For a valid MDS blob, send a valid ServerAuthenticatorAttestationResponse with FULL "packed" attestation by authenticator from that blob and check that server succeeds.‣
Error: Server responed with error. The errorMessage is: Authenticator metadata was not found
    at eval (eval at compileCode (js/sandbox.js:25:26), <anonymous>:4528:19)