* Update linter to 1.49.0
* Move vspd into cmd directory.
This is standard practise in Decred golang repos. Especially useful when multiple executables are built from a single repo.
* Ignore bins in new dir.
- Rather than manually downloading and invoking golangci-lint, use the GitHub
action provided by the developers.
- Configure golangci with a config file rather than passing command line args.
This enables the same config to be used locally and on CI without introducing
duplication. It also allows much more flexibililty in configuration than using
CLI args alone.