Support appending to existing code-climate .json file

[mitar]

Your feature request related to a problem? Please describe.

I have a bunch of separate example files in a directory, each is runnable on its own using go run but the directory is not really a Go package and files have conflicting types if you look at them all together. This is why I run:

find _examples -name '*.go' -exec golangci-lint run --timeout 4m --out-format colored-line-number,code-climate:codeclimate.json {} ';'

But the issue is that codeclimate.json gets just the output from the last run of the tool.

Describe the solution you'd like.

That if codeclimate.json output file already exists, additional entries are appended to it.

Describe alternatives you've considered.

To generate individual files first and then with some other JSON processing tool merge them together.

Additional context.

No response