<!-- Please make sure you have read the submission guidelines before
posting an PR -->
<!--
https://github.com/nrwl/nx/blob/master/CONTRIBUTING.md#-submitting-a-pr
-->
<!-- Please make sure that your commit message follows our format -->
<!-- Example: `fix(nx): must begin with lowercase` -->
<!-- If this is a particularly complex change or feature addition, you
can request a dedicated Nx release for this pull request branch. Mention
someone from the Nx team or the `@nrwl/nx-pipelines-reviewers` and they
will confirm if the PR warrants its own release for testing purposes,
and generate it for you if appropriate. -->
## Current Behavior
<!-- This is the behavior we have today -->
## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->
## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->
Fixes #
Webpack-dev-server v5 changed the proxy config to only accept arrays.
This PR adds a migration for JSON proxy config files to automatically do
the conversion for users. If it's not a JSON format, then we log a
warning and point them to the v5 migration page.
<!-- If this is a particularly complex change or feature addition, you
can request a dedicated Nx release for this pull request branch. Mention
someone from the Nx team or the `@nrwl/nx-pipelines-reviewers` and they
will confirm if the PR warrants its own release for testing purposes,
and generate it for you if appropriate. -->
## Current Behavior
<!-- This is the behavior we have today -->
## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->
## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->
Fixes #
