feat: add --experiments flag to replace --experimental (#5767)

- Deprecates the --experimental flag
- Adds a new flag --experiments which supports passing multiple comma-separated values or a wildcard value.
- Exposes a new endpoint /api/v2/experiments that returns the list of enabled experiments.
- Deprecates the field Features.Experimental in favour of this new API.
- Updates apidocgen to support type aliases (shoutout to @mtojek).
- Modifies apitypings to support generating slice types.
- Updates develop.sh to pass additional args after -- to $CODERD_SHIM.

codersdk/experiments.go

@@ -0,0 +1,53 @@
+package codersdk
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+)
+
+type Experiment string
+
+const (
+	// ExperimentVSCodeLocal enables a workspace button to launch VSCode
+	// and connect using the local VSCode extension.
+	ExperimentVSCodeLocal Experiment = "vscode_local"
+)
+
+var (
+	// ExperimentsAll should include all experiments that are safe for
+	// users to opt-in to via --experimental='*'.
+	// Experiments that are not ready for consumption by all users should
+	// not be included here and will be essentially hidden.
+	ExperimentsAll = Experiments{
+		ExperimentVSCodeLocal,
+	}
+)
+
+// Experiments is a list of experiments that are enabled for the deployment.
+// Multiple experiments may be enabled at the same time.
+// Experiments are not safe for production use, and are not guaranteed to
+// be backwards compatible. They may be removed or renamed at any time.
+type Experiments []Experiment
+
+func (e Experiments) Enabled(ex Experiment) bool {
+	for _, v := range e {
+		if v == ex {
+			return true
+		}
+	}
+	return false
+}
+
+func (c *Client) Experiments(ctx context.Context) (Experiments, error) {
+	res, err := c.Request(ctx, http.MethodGet, "/api/v2/experiments", nil)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return nil, readBodyAsError(res)
+	}
+	var exp []Experiment
+	return exp, json.NewDecoder(res.Body).Decode(&exp)
+}