8.0 Feature request Add Fluent helper for DynamicTemplates

[niemyjski]

Is your feature request related to a problem? Please describe.
The new list syntax leaves a lot ot be desired and a bit of a pain to upgrade to.

Describe the solution you'd like
.DynamicTemplates(t => t.DynamicTemplate("idx_text", t1 => t1.Match("text*").Mapping(m1 => m1.Text(mp => mp.AddKeywordAndSortFields()))))

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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