Migration from `actix-web` to `Axum`

[josecelano]

@da2ce7 @WarmBeer and @josecelano agreed to migrate from actix-web to Axum. We also did it on the tracker:

• Reimplement the current HTTP tracker using Axum torrust-tracker#160
• API overhaul: reimplement the current API using Axum torrust-tracker#143

The main reason in this case is we can have the same dependency in all torrust projects and there was no other reason not to do it. But after making the decision, a new issue was opened on the tracker:

torrust/torrust-tracker#324

It seems Axum does not have a well-defined and tested implementation for client request timeouts. That could lead to denial of service attacks since once a client opens a connection, it's never closed automatically if the client is inactive for a long time.

I think we should postpone this issue for the time being @WarmBeer @da2ce7.

Subtasks

• Refactor: extract tag service #187
• Axum API: scaffolding #174
• Axum API: root enpoints #198
• Axum API: about context #178
• Axum API: user context #183
• Axum API: category context #179
• Axum API: settings context #181
• Axum API: tag context #188
• Axum API: torrent context #182
• Axum API: proxy context #180
• Axum API: make it the default implementation #197
• Remove ActixWeb implementation #208

Related issues

• API: Add timeouts for client requests to avoid DoS attack #204
• User authentication should be done in middleware #39

[josecelano]

Hi @da2ce7, I have started with the migration.