Feat: Generate lists from RegExp Patterns

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User Story
Currently lists can be generated from arbitrary HTML tags with an id identifier, for example, anchor tags:

<a id="some id", class="listOf_class", title="Some Title"></a>
Book section to be listed...

As a vuepress author I would like to generate a list of Tasks from vuepress Custom Containers, e.g. a :::details container but I do not want to prepend every such task with an HTML anchor tag:

:::details Task: This could be the list item title

1. Do this
2. Do that
:::

I would like to be able to generate a list of tasks using a Regular Expression which

• matches a particular pattern
• may optionally contain a RegExp Capture Group in braces ^(group)$ to extract the list item title.

For example, I would like to be able to configure glossarify-md like this:

{
   "generateFiles": {
     "listOf": [{ 
       "class": "task",
       "title": "Tasks", 
       "file": "list-of-tasks.md", 
       "pattern": ":::details Task: ([a-zA-Z0-9].*)"
     }]
   }
}

Internally when glossarify-md finds an mdAst text node which matches the given pattern it should generate and prepend the required HTML target element itself by the following algorithm:

Anchorizer Algorithm:

1. Obtain the listOf config that matched against an mdAst text node's value
2. Obtain as target <element class="..."> the class of the listOf config that matched
3. Obtain as target <element title=" " >
   • a) the value extracted by pattern capture group $1 when matched against the mdAst text node value
   • b) the mdAst text node value, if there's no capture group
4. Obtain as target <element id="..."> a length-limited slug of the title extracted in 3. with a unifying number appended

Appending a unifying number is required since there could be another listOf pattern matching the same text node and extracting the identical title which would result in an identical id. Yet the spec of the id-Attribute requires a unique value for the attribute.