Remote access aar architecture issue: can lead to crashes

Description

!2050 (merged) introduced a new way to include the Remote Access code. In debug mode it's a direct module dependency. In release it's done using an aar.

flowchart TD
    A["`**Application**
    :application:app
    ---
     _Wrapper for the whole app_ 
     ---
    - kt (from all modules)
    - assets (from all modules)`"]
    V["`**VLC Android**
    :application:vlc-android
    ---
    _Contains most of the code_ 
    ---
    - kt (players, UI, ...)
    - assets`"]
    R["`**Remote Access module**
    :application:webserver
    ---
    _Contains the Remote Acccess code_ 
    ---
    - kt (ktor, server code, ...)
    - assets`"]
    RA["`**Remote Access aar**
    Maven
    ---
    _Contains the remote access code and assets_ 
    ---
    - kt (ktor, server code, ...)
    - **Doesn't contain :application:vlc-android code but its interface**
    - assets`"]
    A -- Debug: gradle module --> V
    R -- Debug: gradle module --> V
    A -- Debug: gradle module --> R
    A -- Release: aar --> RA
    R -. Publication using Maven .-> RA

The Remote Access (:application:webserver) gradle module needs :application:vlc-android as a dependency to reference the app's classes. It creates a circular dependency between :application:app, :application:webserver and :application:vlc-android.

Now, let's consider this commit: 4bc91456

It changes the signature of the NetworkProvider class constructor that is used in the remote access module. As the added argument is nullable, this signature change doesn't cause any build issue, neither in debug, nor in release.

But because the release version uses the aar instead of compiling the Remote Access code, at runtime it will cause this crash:

java.lang.NoSuchMethodError: No direct method <init>(Landroid/content/Context;Lorg/videolan/tools/livedata/LiveDataset;Ljava/lang/String;)V in class Lorg/videolan/vlc/providers/NetworkProvider; or its super classes (declaration of 'org.videolan.vlc.providers.NetworkProvider' 

This is due to the signature difference in bytecode between the aar version (that has not been updated between 4bc91456 and the release) and the compiled version (in the release process).

We want to avoid those crashes that cannot be detected or avoided without a lot of constraints.

Architecture change proposal

The reason we decided to publish the Remote Access as a standalone aar, is because the Remote Access client code has to be compiled with another build system (npm) and that external builders (F-Droid) cannot do that. It was an easy way to make the Remote Access available to them.

Given the problem it causes, we think it's better to change the architecture that way:

flowchart TD
    A["`**Application**
    :application:app
    ---
     _Wrapper for the whole app_ 
     ---
    - kt (from all modules)
    - assets (from all modules)`"]
    V["`**VLC Android**
    :application:vlc-android
    ---
    _Contains most of the code_ 
    ---
    - kt (players, UI, ...)
    - assets`"]
    R["`**Remote Access module**
    :application:webserver
    ---
    _Contains only the kotlin code_ 
    ---
    - kt (ktor, server code, ...)`"]
    RC["`**Remote Access client module** ✨
    :application:remoteaccess-client
    ---
    _Contains only the client JS code_ 
    ---
    _No kt code_
    _Only the script cloning and building (npm)_
    - assets`"]
    RAP("`Remote Access project
    ---
    _JS code_`")
    RA["`**Remote Access aar**
    Maven
    ---
    _Contains the remote access client code_ 
    ---
    - JS assets, no kt`"]
    A -- gradle module --> V
    R -- gradle module --> V
    A -- gradle module --> R
    R -- Debug: gradle module --> RC
    R -- Release: aar --> RA
    RC -. Publication using Maven .-> RA
    RC <-. Clone, puts in assets .-> RAP

We will have to:

• create a new :application:webserver-client module
• make it so it clones the Remote Access JS project, builds it and puts it in the assets
• make :application:webserver depend on it
• change the aar to be built with :application:webserver-client and embed only the JS assets