The upstream version of littlefs is what we call littlefs2.
'littlefs' is kept for legacy compatibility, but is not actively
developed upstream.
So make littlefs2 the default for the filesystem example.
- Decluttered Makefile by moving BOARD_INSUFFICIENT_MEMORY lists from Makefile
to Makefile.ci
- Optimized the list for use of tools:
- One entry per line reduces the number of merge conflicts
- One entry per line allows alphabetical sorting e.g. via Vim's sort command
- Sorted all lists alphabetically
Added arduino-nano to BOARD_INSUFFICIENT_MEMORY/BOARD_BLACKLIST following suit
of how arduino-uno is marked, as arduino-nano is mostly an Uno in a different
form factor.
