Razor engine support for text templating

[hikalkan]

Text Templating is currently using Scriban for templating engine.

@maliming has created a library to use Razor View Engine to create templates: https://github.com/maliming/Owl.RazorTemplate/tree/main/src/Owl.RazorTemplate

I think we can make this an official package.

Currently, we have Volo.Abp.TextTemplating package which depends on Scriban.

• Create a Volo.Abp.TextTemplating.Abstractions package that is independent from Scriban and does not include the actual implementation. Move Scriban independed code here.
• Create Volo.Abp.TextTemplating.Scriban depends on Volo.Abp.TextTemplating.Abstractions and implement it with Scriban.
• Create Volo.Abp.TextTemplating.Razor depends on Volo.Abp.TextTemplating.Abstractions and implement it with Razor.

This will be breaking change if we do it like that. To make it backward compatible, we can keep the current Volo.Abp.TextTemplating as an empty package (just a module class) that depends on Volo.Abp.TextTemplating.Scriban.