gracefully handle JNI errors during ConnectedWallet.connect()

[overheadhunter]

See cryptomator/cryptomator#1694:

Loading the FFI libs may fail, in which case we expect KDEWallet to not be available instead of the application crashing. Catching the UnsatisfiedLinkError in here should fix this:

integrations-linux/src/main/java/org/cryptomator/linux/keychain/KDEWalletKeychainAccess.java

Lines 81 to 88 in d73b316

	static Optional<ConnectedWallet> connect() {
	try {
	return Optional.of(new ConnectedWallet(getNewConnection()));
	} catch (DBusException e) {
	LOG.warn("Connecting to D-Bus failed.", e);
	return Optional.empty();
	}
	}

[overheadhunter]

(See also cryptomator/cryptomator#2308)