feat: enable enterprise users to specify a custom logo (#5566)

* feat: enable enterprise users to specify a custom logo

This adds a field in deployment settings that allows users to specify
the URL to a custom logo that will display in the dashboard.

This also groups service banner into a new appearance settings page.
It adds a Fieldset component to allow for modular fields moving forward.

* Fix tests

codersdk/appearance.go

@@ -0,0 +1,43 @@
+package codersdk
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+)
+
+type AppearanceConfig struct {
+	LogoURL       string              `json:"logo_url"`
+	ServiceBanner ServiceBannerConfig `json:"service_banner"`
+}
+
+type ServiceBannerConfig struct {
+	Enabled         bool   `json:"enabled"`
+	Message         string `json:"message,omitempty"`
+	BackgroundColor string `json:"background_color,omitempty"`
+}
+
+func (c *Client) Appearance(ctx context.Context) (AppearanceConfig, error) {
+	res, err := c.Request(ctx, http.MethodGet, "/api/v2/appearance", nil)
+	if err != nil {
+		return AppearanceConfig{}, err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return AppearanceConfig{}, readBodyAsError(res)
+	}
+	var cfg AppearanceConfig
+	return cfg, json.NewDecoder(res.Body).Decode(&cfg)
+}
+
+func (c *Client) UpdateAppearance(ctx context.Context, appearance AppearanceConfig) error {
+	res, err := c.Request(ctx, http.MethodPut, "/api/v2/appearance", appearance)
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return readBodyAsError(res)
+	}
+	return nil
+}