a maintenance release, sort of

Notes:

• partial app rewrite for opencv 4.12. Everything should look and act the same (the changes are as minimal as possible), but we basically swapped out the engine of the car.
• the release apk now uses a custom opencv build (.so) for size and speed reasons. (https://github.com/sz3/opencv-tinyso/releases/tag/v4.12)
• performance improvements: Code should run faster (cooler) than everything since the older opencv 4.4 builds. Hooray?
• newer NDK, newer gradle, misc other dependency upgrades. Blah blah blah

See also:
#67
sz3/libcimbar#162
sz3/libcimbar#164
sz3/libcimbar#161

Misc:

• we're going to give the arm32 build another try. Stay tuned!