plausible deniability (#946)

* Added requestPadding property to all VerficationService requests

* Added fake calls to the WebReqeustBuilder

* 

 initial draft to enable plausible deniability

* Switched from SubmissionConstants to KeyType enum everywhere

* basic playbook implementation with fake and real requests

* Playbook
- ensure request pattern for playbooks is always the same

VerificationService
- apply padding to ensure equal request size (header & body)

SecurityHelper
- extract hash256 to HashHelper. This simplifies tests that use only the hash function (and therefore don´t need to initialize SecurityHelper and its dependencies)

* Implemented random chance of dummy playbook execution on app open

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Playbook
- ignore exceptions for fake requests

SubmissionService
- add padding header to fake request for same header size

WebRequestBuilder
- include fake keys in upload (

)

* DiagnosisKeyService: removed (low value & difficult to test)

SubmissionService & SubmitDiagnosisKeysTransaction
- inline playbook & backgroundNoise property to prevent issues during testing

DiagnosisKeyConstantsTest, SubmissionServiceTest, SubmitDiagnosisKeysTransactionTest & SubmissionViewModelTest
- adjusted to changes

* Dummy playbook will now be repeated and delayed randomly

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Linting

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Initial Code for background noise worker

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* First implementation of noise background worker

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* Linting

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* PlaybookImpl
- ensure that fake requests are executed when real requests fail

SubmissionService & VerificationService
- adjust header name for padding

WebRequestBuilder
- add padding to dummy submission

* BackgroundNoise is now trigger-only

PlaybookImpl
- include follow-up executions after every playbook
- logging

SubmissionViewModel.kt, SubmissionService.kt, SubmitDiagnosisKeysTransaction.kt, MainActivity.kt, BackgroundNoisePeriodicWorker.kt, DiagnosisTestResultRetrievalPeriodicWorker.kt
- propagate context for coroutine

VerificationService
- ensure body size of 1000

* WebRequestBuilder.kt
- adjust fake key generation

PlaybookImplTest.kt
- remove unused server.enqueue

SubmissionService.kt 6 SubmitDiagnosisKeysTransaction.kt
- remove commented out code

* revert temporary changes to SubmissionResultPositiveOtherWarningFragment.kt

* Background job scheduling implemented

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* - adjust fake key size
- remove temporary comment

* Moved build work calls to own file to fix linting

Signed-off-by: Kolya Opahle <k.opahle@sap.com>

* - initialize coroutine scope within the playbook, revert passing it from outside
- remove experimental test dependency for coroutines

* - use single endpoint per server for fake requests
- reduce request size from 1000 to 250 for the verification server
- include dummy registration token in fake request to fulfill verification on server side
- prepare for randomized count of submitted keys
- always include headers cwa-authorization & cwa-header-padding for submission server

* - simplify empty header using constant

Co-authored-by: Kolya Opahle <k.opahle@sap.com>