Fix import with schema=false

[tstirrat15]

Fixes #509

Description

There's a couple of misbehaviors around zed import that we want to fix:

• The command fails if the validation file doesn't have a schema even if schema=false is passed
• The command overwrites the schema if a schema is provided and schema=false is passed

Neither of these is desirable. This PR adds tests for those.

It also fixes an issue with color output breaking tests locally for Linux users.

Changes

TODO

Testing

TODO