Implement Algolia converter collection builder.

[acoumb]

Current PR contains the refactoring of converters using the existing CMS and Forms collection builders, allowing developers to append their own custom converters for Algolia, or to replace one of the default five converters I've added.

The current default converters are intended for the following Umbraco property editors:

• Umbraco.TrueFalse
• Umbraco.Decimal
• Umbraco.Integer
• Umbraco.MediaPicker3
• Umbraco.Tags

To create a new converter one should implement the IConverter interface, specify the name of the property editor and add the new implementation. Then the new converter will need to be added to the Algolia Converters collection.

For example (this will be added to the docs aswell), to remove the existing tags converter, I will ...

1. Create the converter

2. Replace existing converter with the new one

3. Inject custom converters

With this update, I have also addressed these issues:

• 151

• 150

• 149 (picked some of the recommendations from this PR #153 )