IBX-5048: Fixed handling nested lists with line feeds

[vidarl]

Question	Answer
JIRA issue	IBX-5048
Bug/Improvement	yes
New feature	no
Target version	2.3
BC breaks	no
Tests pass	yes/no
Doc needed	no

<itemizedList> and <orderedList> cannot be below <literallayout> in richtext. It was quite hard to deal with that in XSLT, so created a php converter to deal with it after XSLT has completed

TODO:

• Implement feature / fix a bug.
• Implement tests.
• Fix new code according to Coding Standards ($ composer fix-cs).
• Ask for Code Review.

[vidarl]

@ezsystems/php-dev-team : Please review

[alongosz]

@vidarl please see first my last diff comment, it contains all the suggested changes for ListLineBreaks class from other comments to make it more clear.

[vidarl]

I believe all review comments have been addressed now. Feel free to have a final look

[jwibexa]

tested and validated.
Please take note that the PR requires additional line in composer.json:

    "autoload": {
        "psr-4": {
            "App\\": "src/",
+            "Ibexa\\FieldTypeRichText\\RichText\\": "vendor/ezsystems/ezplatform-richtext/src/lib/RichText"
        }
    },