[2.0] Proposal: introduce new Heading aliases

[stsrki]

We have a Heading component. To be able to define its size, we need to define it with the Size parameter

<Heading Size="HeadingSize.Is1">h1. Blazorise heading</Heading>
<Heading Size="HeadingSize.Is2">h2. Blazorise heading</Heading>

I propose to simplify the syntax a little by introducing the new Heading1 to the Heading6 component. Essentially, they will just be inherited from the existing Heading component, with all its parameters intact. But it will be a little easier to write it down.

Example

<Heading1">h1. Blazorise heading</Heading1>
<Heading2">h2. Blazorise heading</Heading2>