feat(data/vector2): induction principle, define last, and some lemmas (blocked by #4578) (#4554)
feat(data/vector2): induction principle, define last, and some lemmas (blocked by #4578) (#4554)



Co-authored-by: Yury G. Kudryashov <2c59405d0ec2e119a1c3d2318bdb4a6ce50051ae@urkud.name>
Co-authored-by: Bryan Gin-ge Chen <6e05157ce10643a7cfc5a3d4e29e4fa5cffe1fc6@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib