fuzzamoto-cli: Add Stability command for showing unstable functions

[tokatoka]

This is a demonstration for one use case of the StabilityStage that I added #86

basically it can summarize what functions were marked as unstable based on the corpus found during the fuzzing run.

It works like this:

1. StabilityStage identifies unstable testcases and keep a list of them.
2. For those unstable testcases, we run the same cases for multiple times (10 times) and gather the profraw files.
3. We check the profraw files and compute which are unstable.

You can try this with a command like this

/fuzzamoto/target/release/fuzzamoto-cli stability --output /mnt/output --corpus /mnt/corpus --llvm-profparser /llvm-profparser/target/release/profparser --unstable-testcases <file of unstable testcase names> --bitcoind /bitcoin/build_fuzz_cov/bin/bitcoind --scenario <scenario name>

"list of unstable testcases" corresponds to the file specified in the StabilityStage's 3rd argument

[dergoegge]

This needs a rebase, the stage has been merged