cloudflareDevProxyVitePlugin: support wrangler environments

[parisholley]

if environment variables and bindings are prefixed to an environment, they aren't read by cloudflareDevProxyVitePlugin(). this can be worked around by moving a development environment config into a different wrangler.toml file and reference with configPath, but would prefer to have a single file and pass an "environment" argument to cloudflareDevProxyVitePlugin