Add system activity tracking and event store (#636)

This PR adds system activity tracking. 
The management service records events like 
add/remove peer,  group, rule, route, etc.

The activity events are stored in the SQLite event store
and can be queried by the HTTP API.

management/server/http/events.go

@@ -0,0 +1,69 @@
+package http
+
+import (
+	"fmt"
+	"github.com/netbirdio/netbird/management/server"
+	"github.com/netbirdio/netbird/management/server/activity"
+	"github.com/netbirdio/netbird/management/server/http/api"
+	"github.com/netbirdio/netbird/management/server/http/util"
+	"github.com/netbirdio/netbird/management/server/jwtclaims"
+	log "github.com/sirupsen/logrus"
+	"net/http"
+)
+
+// Events HTTP handler
+type Events struct {
+	accountManager server.AccountManager
+	authAudience   string
+	jwtExtractor   jwtclaims.ClaimsExtractor
+}
+
+// NewEvents creates a new Events HTTP handler
+func NewEvents(accountManager server.AccountManager, authAudience string) *Events {
+	return &Events{
+		accountManager: accountManager,
+		authAudience:   authAudience,
+		jwtExtractor:   *jwtclaims.NewClaimsExtractor(nil),
+	}
+}
+
+// GetEvents list of the given account
+func (h *Events) GetEvents(w http.ResponseWriter, r *http.Request) {
+	claims := h.jwtExtractor.ExtractClaimsFromRequestContext(r, h.authAudience)
+	account, user, err := h.accountManager.GetAccountFromToken(claims)
+	if err != nil {
+		log.Error(err)
+		http.Redirect(w, r, "/", http.StatusInternalServerError)
+		return
+	}
+
+	accountEvents, err := h.accountManager.GetEvents(account.Id, user.Id)
+	if err != nil {
+		util.WriteError(err, w)
+		return
+	}
+	events := make([]*api.Event, 0)
+	for _, e := range accountEvents {
+		events = append(events, toEventResponse(e))
+	}
+
+	util.WriteJSONObject(w, events)
+}
+
+func toEventResponse(event *activity.Event) *api.Event {
+	meta := make(map[string]string)
+	if event.Meta != nil {
+		for s, a := range event.Meta {
+			meta[s] = fmt.Sprintf("%v", a)
+		}
+	}
+	return &api.Event{
+		Id:           fmt.Sprint(event.ID),
+		InitiatorId:  event.InitiatorID,
+		Activity:     event.Activity.Message(),
+		ActivityCode: api.EventActivityCode(event.Activity.StringCode()),
+		TargetId:     event.TargetID,
+		Timestamp:    event.Timestamp,
+		Meta:         meta,
+	}
+}