Justify feature for text

[ReformatDuckhunt]

This feature adds text alignment support to the PDF printer, including:

• Center alignment
• Left alignment
• Right alignment (implemented with a small workaround, as the actual string width is not yet accurately determined)

[sonntagd]

Hi @ReformatDuckhunt
thanks for your PR!
In my applications I am mainly using the ->utf8ImagedText way, but isnt the normal ->text method just using monospaced fonts? If yes, one could replace the text width guessing by indenting the centered/right-aligned text with a well-calculated number of spaces.