Sync up with changes from voting branch

[ManfredKarrer]

There have been several changes in the voting branch (and api-integration) which I want to get into master to avoid that those branches run out of sync as well as to apply the improvements.
The main changes are:

• The handling of persisted data in the p2p library (Change data persitence  bisq-p2p#8)
• Improvements of the app setup to support API projects in headless mode as well as in mixed mode
• Use custom TxBroadcaster class for better error handling

Beside that there are many smaller trivial improvements, fixes, refactoring and cleanups.

Changes in that project:

• Add DaoOptionKeys.DAO_ACTIVATED option key
• Add setupDevEnv, onApplicationStarted and startAppSetup to
  BisqExecutable
• Rename BisqCoreApp to BisqHeadlessApp
• Rename BisqCoreAppMain to BisqHeadlessAppMain
• Add BisqSetupCompleteListener interface to BisqSetup
• Remove @getterS from BisqSetup handlers
• Change handling of setup complete handlers
• Remove Objects.requireNonNull and use null checks instead
• Add HeadlessApp class
• Add TxBroadcaster class with improved error handling
• Add TxBroadcastException and TxMalleabilityException
• Use TxBroadcaster.Callback instead of FutureCallback
• Remove Broadcaster
• Fix wrong dust limit value in comments
• Remove delay at updateBalance
• Add AccountAgeWitnessStorageService and TradeStatistics2StorageService
• Move BtcAddressValidator from desktop to core
• Move old setup classes to bisq.core.app.misc

[sqrrm]

utACK

I've been developing on top of these change for a while with no issues, but also haven't used some of the features so not a complete test.

[ripcurlx]

ACK - see bisq-network/bisq#1601 (comment)