Align RichText heading styles and font sizes with OOB SharePoint text web part

[mbice]

Q	A
Bug fix?	[x]
New feature?	[ ]
New sample?	[ ]
Related issues?	fixes #X, partially #Y, mentioned in #Z

What's in this Pull Request?

The out-of-the-box SharePoint text web part has changed over the past year and looks different than the RichText component in several ways. This PR aligns the RichText component so it's more close to the out-of-the-box text web part. The following alignments were made.

• Update styles dropdown strings for headings (e.g. instead of Heading 1 to 3 it's now Heading 2 to 4). Also moved the "Normal text" option below the headings to match with SharePoint text web part.
• Update font sizes to match out-of-the-box. This includes the font size options in the dropdown AND the font sizes applied in the CSS. Headings and text in the RichText component should now match SharePoint text web part.
• Update pull quote styling to match SharePoint text web part.

Thanks!

[joelfmrodrigues]

@mbice many thanks and sorry for the delay, this is now merged