Move @types/ packages to devDependencies

[lpsinger]

TypeScript type packages are normally dev-only dependencies. You generally only need types for development, not at run time.

Which problem is this PR solving?

• Excessive size of node_modules directory when using these plugins.

Short description of the changes

• Move all @types/ packages from dependencies to devDependencies.
• Update GUIDELINES.md.

[Flarna]

Have you ensured that these types are not used in any pubic API?
Otherwise consumers end up with typescript issues because of missing types.

The issue tracker holds a few such issues and there are a few PRs moving types from/to dev deps. e.a. #802

#1320 shows how to remove types dependencies in API surface to move them into dev deps without causing problems.

https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/GUIDELINES.md holds also some more details.

[lpsinger]

Oh dear. This is more complicated than I at first realized.

[Flarna]

@lpsinger I fully understand that you closed this PR.
But you are really welcome to contribute in this are. Likely not by a single big bang PR but maybe one by one.

[lpsinger]

No worries, I understand.

I was looking at the AWS Distro for OpenTelemetry Lambda layer and I was surprised to find the type modules inside it.