Add new tests for multiple creations of account and outbound group sessions: check random generation function in JNI works properly

Rename local parameter properly

- previously the random seed was seconds based, and it could originate identical identity keys for different OlmAccount

- add a buildJavaDoc task in build.gradle
- update classes javadoc headers

- add logs in verifyEd25519SignatureJni() to print the key used

Add sanity tests for OlmAccount and OlmSession
Add a first version of MatchInboundSession

An error code is now returned, no utility to return the object itself (initial implementation matching iOS)

Fix removeOneTimeKeysForSession() default return code

- generateOneTimeKeys => generateOneTimeKeysJni
- maxOneTimeKeys => maxOneTimeKeysJni

- for 32bits platform target
- when debug flag is not defined

- remove compiler warnings when logs are not enabled
- new getInstanceId() function to refactor code

- new JNI API: serializeDataWithKeyJni() and initWithSerializedDataJni()
- update account unit test
- modify OlmAccount constructor API: an exception may be thrown

Fix verifyEd25519Signature() API to properly return the error message in case signature verification failed
- update unit tests

- add unit tests for OlmUtility
- rename OlmGroupTest to OlmGroupSessionTest
- update OlmException

- Introducing namespace AndroidOlmSdk
- Fix logs (function names mixed up)
- Add new check based on the calling java object instance type (IsInstanceOf())
- Fix return value for getXXXInstanceId() in case of failure. Now 0 is returned.

- change return code from removeOneTimeKeysForSession() (direct value from JNI is now returned)