A newer release of Docker (27.3.1) appears to have issues with the -p flag appearing the same time more than once for a given port. This was previously not an issue, but we should remove the problem on our end regardless.
Closes#7251
Previously, we would always set the port mapping during a dockerfile build, making it difficult for users to override mappings. We also only _sometimes_ updated the detected port mapping, further confusing issues when users were migrating from Dockerfile to Buildpacks for builds.
Now, we always detect the port mapping during the build process, and only use that detected port mapping if an override is not specified. This greatly simplifies the experience around port mapping, as now a user can create an app, set a port mapping, and that first deploy will respect the port mapping without an additional deploy.
The builder always has the best context for what the app should be listening on, and thus we can always specify a "default" port mapping at this stage. Users can override this map as desired later.
This change also results in the removal of a ton of internal code that is now centralized in the ports plugin.
Closes#4067
The link flag was previously not filtered _after_ fetching build args for dockerfile builds, which meant if a plugin exposed that in it's own docker-args-build trigger, it would break deploys.
Additionally, allow for whitespaces between link and volume flags.
