Previously, if you were using project names and you had two projects
with the same directory and workspace but different workflows, running
"atlantis apply" would fail. This was because we weren't figuring out
what the project name was for each pending plan.
This change fixes this by extracting the project name from the planfile.
We also handle /'s in the project name by substituting them with '::'.
This allows us to convert them back to /'s when we're figuring out the
project names from the filenames. It's safe to do this because : isn't
an allowed character for project names.
We also remove a final substitution of invalid filename characters
because we rely on the validation of the project names instead which
happens when validating the atlantis.yaml file.
We should only allow project names (which are specified in an
atlantis.yaml file) that don't need to be url escaped. The one
exceptional character is '/' which we allow because users like to name
their projects to match the directory they're in. We use the same rule
that Terraform uses for workspace names.
I've also changed the characters that are replaced when writing out the
plan filename to only remove invalid filename characters instead of just
allowing alphanumeric. This is the smallest amount of change required to
ensure the filename is valid.
