Create convert to boolean process plugin

As requested! :)

This uses the php boolval() function. It also accounts for yes/no strings.

Thank you for the contribution @edmund.dunn I will take a look at this soon.

Somehow the first one ended up empty. This one has the patch.

I think this solution is a little too restrictive as string versions of true or false both evaluate to 1

php > boolval('true');
php > echo boolval('true');
1
php > echo boolval('false');
1
php > echo boolval('FALSE');
1
php > echo boolval('TRUE');
1

This creates a situation where we have a bypass mapping for 'yes' and 'no' but none for 'TRUE' or 'FALSE' or 'null', or 'NULL'. I'll re-work this a bit to give more predictable results and also allow mapping for other values that might not be English.

I modified this to allow for config based string mapping.

Simple

  field_boolean:
    plugin: convert_boolean
    source: boolean

Using optional mapping

  field_boolean:
    plugin: convert_boolean
    source: boolean
    map_true:
      - yes
      - Yes
      - si
    map_false:
      - no
      - No
      - nada

This will go out with 8.x-2.7

Automatically closed - issue fixed for 2 weeks with no activity.