Add config option to enable json logging

[MrKaplan-lw]

This is backported from 97772b9

#5471
97772b9

This introduces a bit of code duplication due to type differences when json vs non-json logging are used in combination with opentelemetry.
As opentelemetry has been removed in main it's simpler there.

[MrKaplan-lw]

CI fails due to SQL formatting in migrations, but they weren't touched in this PR

[Nutomic]

Only this part needs to be inside the if, something like this:

let layer = if settings.json_logging {
    tracing_subscriber::fmt::layer().with_ansi(false).json();
} else {
    tracing_subscriber::fmt::layer().with_ansi(false).json();
}
let format_layer = layer.with_filter(targets.clone());
...

Then its not necessary to write all the stuff for opentelemetry etc twice.

[MrKaplan-lw]

you included .json() there twice.

i've tried to do it that way first but it won't compile due to different types being returned by the if branches:

   Compiling lemmy_server v0.19.10 (.../lemmy)
error[E0308]: `if` and `else` have incompatible types
   --> src/lib.rs:401:5
    |
398 |     let layer = if settings.json_logging {
    |  _______________-
399 | |     tracing_subscriber::fmt::layer().with_ansi(false).json()
    | |     -------------------------------------------------------- expected because of this
400 | |   } else {
401 | |     tracing_subscriber::fmt::layer().with_ansi(false)
    | |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Layer<_, JsonFields, Format<Json>>`, found `Layer<_>`
402 | |   };
    | |___- `if` and `else` have incompatible types
    |
    = note: expected struct `tracing_subscriber::fmt::Layer<_, JsonFields, tracing_subscriber::fmt::format::Format<tracing_subscriber::fmt::format::Json>>`
               found struct `tracing_subscriber::fmt::Layer<_, DefaultFields, tracing_subscriber::fmt::format::Format<tracing_subscriber::fmt::format::Full>>`

perhaps this could be solved with an explicit more generic type annotation, but i'm not sure which one it would need.

[Nutomic]

CI is fixed with #5558 so you can merge those changes.

[dessalines]

Make sure to do this PR to main also.

[Nutomic]

This is a backport from main to 0.19

[MrKaplan-lw]

@Nutomic it seems that you have mixed up branch names while backporting other changes.

the branch release/v0.19, which was previously used for tracking 0.19 updates, only has 2 commits since 0.19.10, but the branch release/0.19 has various other backports you did.