Config setting to override image pull credentials type

The `aws codebuild start-build` command in the AWS CLI has a parameter `--image-pull-credentials-type-override` to override the service role used to pull/provision the custom images in a AWS CodeBuild build project.

Unfortunately the AWS CodeBuild Jenkins Plugin seems to be missing this configuration setting.

https://docs.aws.amazon.com/cli/latest/reference/codebuild/start-build.html

> `--image-pull-credentials-type-override (string)`
>
> The type of credentials AWS CodeBuild uses to pull images in your build. There are two valid values:
>
> `CODEBUILD`
> Specifies that AWS CodeBuild uses its own credentials. This requires that you modify your ECR repository policy to trust AWS > CodeBuild's service principal.
>
> `SERVICE_ROLE`
> Specifies that AWS CodeBuild uses your build project's service role.
>
> When using a cross-account or private registry image, you must use `SERVICE_ROLE` credentials. When using an AWS CodeBuild curated image, you must use `CODEBUILD` credentials.
>
> Possible values:
>
> * `CODEBUILD`
> * `SERVICE_ROLE`

Start by tracing the Jenkins plugin's build-step configuration and the request built for the AWS CodeBuild start-build operation. Add the missing image-pull-credentials-type override with the CODEBUILD and SERVICE_ROLE values described in the issue, then verify that the selected value is included in the build request.

Written by the indexing model from the issue text.