Formatting map literals

Should map values be aligned, or should they have a single space between keys and values? E.g.:

```clj
{:a 1
:xyz 2}

;; or

{:a 1
:xyz 2}
```

Do we want to control formatting of whitespace within a map values at all? (probably)
How do we handle formatting maps when you have several but not all key-value pairs on the same line?
How do we handle formatting maps when the value is put on the line below the key? e.g.

```
{:a 1
:b
2}

;; or

{:a 1
:b
2}
```

Aligning map values may lead to more readable code (at least for some people) but can introduce more churn in source control diffs as keys are added and removed over time. There are often ways to remove whitespace from diff views, but this may still be an issue for some people.

No files, tests, or entry points are identified in the issue. Start by resolving the formatting policy for aligned and multiline map values, including mixed inline and multiline pairs. Done means the behavior is specified clearly enough to implement and verify.

Written by the indexing model from the issue text.