Replace serde with serde_core when possible

[AdamGS]

Which issue does this PR close?

• Closes Change serde dependency to serde_core where applicable #8451.

With this change, its possible to compile the core crate without pulling serde_derive, which is will be only required for arrow-avro and arrow-schema/serde.

Rationale for this change

Improve compile time and reduce number of dependencies and binary size in some cases.

What changes are included in this PR?

1. Use serde_core when possible
2. Manually implement Serialize/Deserialize for canonical extension type metadata.

Are these changes tested?

Covered by existing tests

Are there any user-facing changes?

No

[crepererum]

my guess is that this is auto-generated code. I personally would prefer if we wouldn't nest structs/enums/impls/etc. into methods. It makes the code rather hard to read (for auto-generated code there are usually good reasons why this is done this way, e.g. due to shadowing).

[AdamGS]

Definitely autogenerated-inspired, I'll pull all the inner definition outside.

[AdamGS]

Done

[crepererum]

This currently is only semi-effective until BurntSushi/rust-csv#403 is merged and released. But if we try this upstream change by adding the following to Cargo.toml:

[patch.crates-io]
csv = {git = "https://github.com/paolobarbolini/rust-csv.git", branch = "switch-to-serde-core"}

and then we get all crates for a full-featured arrow (but without dev dependencies because criterion uses derive-based serialization):

$ cargo tree -p arrow --all-features -e=no-dev

then there's no serde_derive left and no syn and no proc-macro2. So I would call this a win.