lint: add "make lint" target, run it from ci

See https://github.com/tinygo-org/tinygo/issues/4225

Runs in both circleci and github, circleci is run on branch push, github is run on PR

Revive builds so fast, don't bother installing it; saves us wondering which one we get

Uses tools.go idiom to give control over linter versions to go.mod.

Also pacifies linter re AppendToGlobal as a token first fix.

TODO: gradually expand the number of directories that are linted,
uncomment more entries in revive.toml, and fix or suppress the
warnings lint finds.

TODO: add linters "go vet" and staticcheck

NOT TODO: don't add metalinters like golangci-lint that pull in
lots of new of dependencies; we'd rather not clutter go.mod that
much, let alone open ourselves up to the additional attack surface.

.github/workflows/linux.yml

@@ -113,6 +113,8 @@ jobs:
           gem install --version 4.0.7 public_suffix
           gem install --version 2.7.6 dotenv
           gem install --no-document fpm
+      - name: Run linter
+        run: make lint
       - name: Build TinyGo release
         run: |
           make release deb -j3 STATIC=1