0.8 compat

Add 0.8 migration (#278)

* feat: upgrade contracts to solidity 0.8

* feat: continue with 0.8 migration

- Remove audits
- Remove NFTDescriptor stuff because couldn't easily work through
  a weird assembly stacktoodeep issue. I think it has to do with
  ABIcoderv2

* fix: package.json

* fix: tests for 0.8 migration

* fix: clean up comment

* feat: upgrade to 0.8.15

* fix: bump version

* Fix code style issues with Prettier

* fix: improve gas for liquidityamounts

* Fix code style issues with Prettier

* fix: review comments

- add back nft descriptor tests
- remove xits
- improve ticklens gas

* Fix code style issues with Prettier

Co-authored-by: Lint Action <[email protected]>