chore: add fvuls image

[MaineK00n]

What did you implement:

When master and tag are pushed, a Docker image for FutureVuls is also created.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

manual build

$ docker build -t vuls/fvuls -f ./contrib/Dockerfile .
$ docker run -it --rm vuls/fvuls /bin/sh
/vuls # vuls -v
vuls v0.19.4 build-20220323_024728_a1cc152e
/vuls # trivy-to-vuls version
trivy-to-vuls-v0.19.4-build-20220323_024821_a1cc152e
/vuls # future-vuls version
future-vuls-v0.19.4-build-20220323_025131_a1cc152e

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES

Reference

[kotakanbe]

LGTM