Use the struct-initialization linter more

[eljobe]

In much of the go codebase, we use and initialize structs.

In most of those places, we should really ensure that all fields on the struct are explicitly initialized. This helps to ensure that new fields on structs aren't just silently getting the zero value for that type without anyone noticing.

We can annotate each struct initialization with:

// lint:require-exhaustive-initialization

To ensure that structs are exhaustively initialized.

One example of this is:

nitro/linters/testdata/src/structinit/a/a.go

Line 5 in 7fd92fa

// lint:require-exhaustive-initialization

But, that's just in the linter test. We want to start adopting this in more places in our codebase with the eventual goal of making the linter-opt out once the majority of struct initializations are exhaustive.

If you open a PR to add this annotation to a struct, be sure to reference this issue in the commit comment.

[Tristan-Wilson]

The lint:require-exhaustive-initialization directive should be placed directly above struct definitions, not initializations. When added, it enforces that all fields must be explicitly initialized when creating instances of that struct.

See the example:

nitro/linters/testdata/src/structinit/a/a.go

Line 5 in 7fd92fa

// lint:require-exhaustive-initialization

So perhaps we should change the guidance for this issue to say that we should add it to select definitions that we care about being fully initialized?