feat: Expose ECR image to use in other services - like AWS Batch

[MengLinMaker]

I would be great to abstract away some implementation jank to gain access to ECR images. This would provide a much better default developer experience.

For context, I'm deploying AWS Batch using SST which requires uploading images to ECR - refer to #6244

This is the current solution - requiring a janky workarounds to find the location and name of dockerfile

import * as pulumi from '@pulumi/pulumi'
import path from 'node:path'

const Repository = new awsx.ecr.Repository('Repository')

// Need to get out of the '.sst/platform' folder to context folder 'src'
const contextPath = '../../src'

// Specify context and dockerfile name to avoid path issues with SST
const Image = new awsx.ecr.Image('Image', {
    repositoryUrl: Repository.url,
    dockerfile: path.join(contextPath, 'dockerfile'),
    context: path.join(contextPath),
})

I'm also using the awsx provider.