## Changes
* Add support for using `databricks.yml` as config file. If
`databricks.yml` is not found then falling back to `bundle.yml` for
backwards compatibility.
* Add support for `.yaml` extension.
* Give an error when more than one config file is found
## Tests
* added unit test
* manual testing the different cases
---------
Co-authored-by: Pieter Noordhuis <pieter.noordhuis@databricks.com>
While working on artifact upload and workspace interrogation I realized
this mutator interface needs to:
1. Operate at the whole bundle level so it can apply to both
configuration and internal state
2. Include a `context.Context` parameter for a) long running operations
and b) progress reporting
Previous interface:
```
Apply(*config.Root) ([]Mutator, error)
```
New interface:
```
Apply(context.Context, *Bundle) ([]Mutator, error)
```