[2.0.0-beta4] MachineName prop & typed data API

Answer : no we won't add typed_data: ['machine_name'] to the MachineNamePropType,
instead we will add machine_name to the typed_data of StringPropType.
This mechanism is only used for source derivers.
typed_datavalue in PHP Attributes of prop types, allow to declare that a Drupal typed data value, can be put in the prop type that is declaring the typed data. Here we have a machine_name drupal typed data that can go into a string prop type.
Furthermore, with the mechanism in place, specifying machine_name in typed_data array values of StringPropType, will allow each machine_name field property to be available as a source plugin and declared as a string.

Now about HTML IDs. After some web search queries and reading:
- HTML ids could be any unicode character without spaces according to the supposed "standard". See [this link](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/id) for example.
- In practice, we want html ids to be used as CSS identifiers with CSS or JS. this adds some restrictions. See [this other link](https://developer.mozilla.org/en-US/docs/Web/CSS/ident) for example.

i pushed the work :
- The regex has been extended.
- I did a rapid check of unhandled simple typed data from core, and i found 'machine_name' and 'filter_format'. I added them to the string prop type php attributes, allowing for more derived field prop than before.

So, machine_name types data was added to StringPropType instead of MachineNamePropType.

I will have a look.

Let's rename machine_name by identifier and MachineNamePropType by IdentifierPropType.

This prop type comply with: https://developer.mozilla.org/en-US/docs/Web/CSS/ident
See also: https://developer.mozilla.org/en-US/docs/Glossary/Identifier

It would be nice to mention those URL in description and/or comment.

And update the converter:

--- a/modules/ui_patterns_legacy/src/PropConverter.php
+++ b/modules/ui_patterns_legacy/src/PropConverter.php
@@ -25,7 +25,7 @@ class PropConverter {
         '$ref' => 'ui-patterns://links',
       ],
       'machine_name' => [
-        '$ref' => 'ui-patterns://machine_name',
+        '$ref' => 'ui-patterns://identifier',
       ],
       'number' => $this->convertNumber($setting),
       'radios' => $this->convertEnum($setting),

And update the tests in:

• modules/ui_patterns_devel/tests/themes/ui_patterns_devel_theme_test/components/all_errors
• tests/modules/ui_patterns_test/components/

this will be a breaking change

Used in some theme. Example:

 $ grep -r machine_name */components/*
ui_suite_uswds/components/nav/nav.component.yml:      $ref: 'ui-patterns://machine_name'
ui_suite_uswds/components/nav_footer/nav_footer.component.yml:      $ref: 'ui-patterns://machine_name'

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