Support configuration option for mapping style format

[dsayling]

Description

It would be great to have a feature like that of export YAMLFIX_SEQUENCE_STYLE="flow_style", but for mappings.

Possibly, export YAMLFIX_MAPPING_STYLE="flow_style"

Possible Solution

Set to true (flow-style):

---
map: { key: val, other: item }

Set to false (block-style):

---
map:
  key: val
  other: item

Additional context

Other possibilities include whatever this style is

---
map:
  {
    key: val
    other: item
  }

Related Issue

None that I could see