Integrate Slither

[nventuro]

We likely don't care much about the base detectors, but can write custom ones that'd be highly useful. E.g. #1940, or checking that past a certain point a contract makes no external calls (which is a useful property to test in e.g. pools).

[jubeira]

After some research, my preliminary conclusion is that slither doesn't play along very well with monorepos.

In short, when it analyzes contracts that have dependencies outside the contracts' own workspace, it is unable to find them and it halts (see crytic/crytic-compile#279). At the moment I didn't find a way to indicate slither how to find those dependencies.

This can potentially be solved if we could indicate where our root node_modules directory is. I've opened a PR with a potential solution in crytic-compile, which is the dependency that handles that: crytic/crytic-compile#301.

[jubeira]

Rule to add when we have it: #1940 (comment)