Refactor: Unify lifespan hooks

[provinzkraut]

Implements #1634, as discussed in #1635.

The following application hooks were removed:

• before_startup
• after_startup
• before_shutdown
• after_shutdown

The hooks on_startup and on_shutdown have been altered to optionally accept an application instance as their only argument. The decision to keep this detail around was made to more easily allow to re-use existing callables and pass them to the hooks, without having to wrap them in another callable which accepts a positional argument.

In addition, the lifespan argument to Litestar et. al was changed to allow instances of AbstractAsyncContextManager alongside callables which return such context managers. This was done to allow e.g. plugins to inject themselves as a lifespan manager.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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100.0% Coverage
0.0% Duplication

[peterschutt]

Very nice!