chore: switch from memfs to fstest.MapFS (#327)

* Switch from memfs to built-in fstest.MapFS
* Ensure httptest servers are closed during test cleanup
* Swap ordering of expected/actual values in assertion functions
* Use http.StatusOK constants for status codes
* Add a 1-second context timeout for each request
* Use the test httptest.Server.Client() so that we can handle
  TLS server certificates if desired

go.mod

@@ -41,7 +41,6 @@ require (
 	github.com/pion/transport v0.13.0
 	github.com/pion/webrtc/v3 v3.1.23
 	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8
-	github.com/psanford/memfs v0.0.0-20210214183328-a001468d78ef
 	github.com/quasilyte/go-ruleguard/dsl v0.3.17
 	github.com/spf13/cobra v1.3.0
 	github.com/stretchr/testify v1.7.0

go.sum

@@ -1104,8 +1104,6 @@ github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4O
 github.com/prometheus/procfs v0.2.0/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
 github.com/prometheus/tsdb v0.7.1/go.mod h1:qhTCs0VvXwvX/y3TZrWD7rabWM+ijKTux40TwIPHuXU=
-github.com/psanford/memfs v0.0.0-20210214183328-a001468d78ef h1:NKxTG6GVGbfMXc2mIk+KphcH6hagbVXhcFkbTgYleTI=
-github.com/psanford/memfs v0.0.0-20210214183328-a001468d78ef/go.mod h1:tcaRap0jS3eifrEEllL6ZMd9dg8IlDpi2S1oARrQ+NI=
 github.com/quasilyte/go-ruleguard/dsl v0.3.17 h1:L5xf3nifnRIdYe9vyMuY2sDnZHIgQol/fDq74FQz7ZY=
 github.com/quasilyte/go-ruleguard/dsl v0.3.17/go.mod h1:KeCP03KrjuSO0H1kTuZQCWlQPulDV6YMIXmpQss17rU=
 github.com/remyoudompheng/bigfft v0.0.0-20190728182440-6a916e37a237/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=