Only build, install u8g2 for the <s>three</s>six targets that need it.

[robertlipe]

Description

Continues like #788 . Fetch, download, and install ug82 for the six targets that need it.

...not the other 47.

Waste less development time and storage space downloading and compiling unneeded code.

Contributing requirements

• [x] I read the contribution guidelines in CONTRIBUTING.md.
• [x] I understand the BlinkenPerBit metric, and maximized it in this PR.
• [x] I selected main as the target branch.
• [x] All code herein is subjected to the license terms in COPYING.txt.