Support scoped access tokens (#20908)

This PR adds the support for scopes of access tokens, mimicking the
design of GitHub OAuth scopes.

The changes of the core logic are in `models/auth` that `AccessToken`
struct will have a `Scope` field. The normalized (no duplication of
scope), comma-separated scope string will be stored in `access_token`
table in the database.
In `services/auth`, the scope will be stored in context, which will be
used by `reqToken` middleware in API calls. Only OAuth2 tokens will have
granular token scopes, while others like BasicAuth will default to scope
`all`.
A large amount of work happens in `routers/api/v1/api.go` and the
corresponding `tests/integration` tests, that is adding necessary scopes
to each of the API calls as they fit.


- [x] Add `Scope` field to `AccessToken`
- [x] Add access control to all API endpoints
- [x] Update frontend & backend for when creating tokens
- [x] Add a database migration for `scope` column (enable 'all' access
to past tokens)

I'm aiming to complete it before Gitea 1.19 release.

Fixes #4300

tests/integration/api_httpsig_test.go

@@ -10,6 +10,7 @@ import (
 	"net/url"
 	"testing"
 
+	auth_model "code.gitea.io/gitea/models/auth"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/tests"
 
@@ -52,7 +53,7 @@ func TestHTTPSigPubKey(t *testing.T) {
 	// Add our public key to user1
 	defer tests.PrepareTestEnv(t)()
 	session := loginUser(t, "user1")
-	token := url.QueryEscape(getTokenForLoggedInUser(t, session))
+	token := url.QueryEscape(getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeAdminPublicKey, auth_model.AccessTokenScopeSudo))
 	keysURL := fmt.Sprintf("/api/v1/user/keys?token=%s", token)
 	keyType := "ssh-rsa"
 	keyContent := "AAAAB3NzaC1yc2EAAAADAQABAAABAQCqOZB5vkRvXFXups1/0StDRdG8plbNSwsWEnNnP4Bvurxa0+z3W9B8GLKnDiLw5MbpbMNyBlpXw13GfuIeciy10DWTz0xUbiy3J3KabCaT36asIw2y7k6Z0jL0UBnrVENwq5/lUbZYqSZ4rRU744wkhh8TULpzM14npQCZwg6aEbG+MwjzddQ72fR+3BPBrKn5dTmmu8rH99O+U+Nuto81Tg7PA+NUupcHOmhdiEGq49plgVFXK98Vks5tiybL4GuzFyWgyX73Dg/QBMn2eMHt1EMv5Gs3i6GFhKKGo4rjDi9qI6PX5oDR4LTNe6cR8td8YhVD8WFZwLLl/vaYyIqd"