Make it possible to configure the output of a boolean field on the formatter level

Problem/Motivation

Currently you can configure the output of a boolean field on a field settings level. For views itself though there are more use cases:

• You want to output 0/1 for raw data output
• For some nice listings, you might want to support some unicode chars
• These are the default options + a fully customizable one.
  $default_formats = array(
  'yes-no' => array(t('Yes'), $this->t('No')),
  'true-false' => array(t('True'), $this->t('False')),
  'on-off' => array(t('On'), $this->t('Off')),
  'enabled-disabled' => array(t('Enabled'), $this->t('Disabled')),
  'boolean' => array(1, 0),
  'unicode-yes-no' => array('✔', '✖'),
  );

While we are converting base fields to use field formatters, this lack of support for boolean formatting causes problems in #2342045: Standard views base fields need to use same rendering as Field UI fields, for formatting, access checking, and translation consistency → . Once #2342045: Standard views base fields need to use same rendering as Field UI fields, for formatting, access checking, and translation consistency → gets in, not having all those options available on the boolean formatter would be a regression.

Proposed resolution

Extend the boolean field formatter with options to support these display formats. This will allow #2342045: Standard views base fields need to use same rendering as Field UI fields, for formatting, access checking, and translation consistency → to not regress functionality for boolean fields.

Remaining tasks

Commit.

User interface changes

Boolean fields have more flexible display formats.

API changes

The boolean formatter schema is slightly expanded.

Beta phase evaluation