Support of auto line break on syntax highlighting

[bells17]

Now not be a new line at the time of the syntax highlighting.

example:

When a character does not fit on the screen,
I think that it should be a new line in the automatic.

[yhatt]

We're making a clean sweep of piled up issues.

Auto line break might break source code. In the core of Marp Next, we have supported auto scaling of code block in several themes (marp-team/marp-core#23). This behavior also has a compatibillity with the other app. (e.g. Deckset)