Fix various permission & login related bugs (#36002)

Permission & protection check:

- Fix Delete Release permission check
- Fix Update Pull Request with rebase branch protection check
- Fix Issue Dependency permission check
- Fix Delete Comment History ID check

Information leaking:

- Show unified message for non-existing user and invalid password
    - Fix #35984
- Don't expose release draft to non-writer users.
- Make API returns signature's email address instead of the user
profile's.

Auth & Login:

- Avoid GCM OAuth2 attempt when OAuth2 is disabled
    - Fix #35510

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/v1/repo/issue_dependency.go

@@ -201,7 +201,7 @@ func CreateIssueDependency(ctx *context.APIContext) {
 		return
 	}
 
-	dependencyPerm := getPermissionForRepo(ctx, target.Repo)
+	dependencyPerm := getPermissionForRepo(ctx, dependency.Repo)
 	if ctx.Written() {
 		return
 	}
@@ -262,7 +262,7 @@ func RemoveIssueDependency(ctx *context.APIContext) {
 		return
 	}
 
-	dependencyPerm := getPermissionForRepo(ctx, target.Repo)
+	dependencyPerm := getPermissionForRepo(ctx, dependency.Repo)
 	if ctx.Written() {
 		return
 	}

routers/api/v1/repo/release_tags.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 
 	repo_model "code.gitea.io/gitea/models/repo"
+	unit_model "code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/convert"
 	release_service "code.gitea.io/gitea/services/release"
@@ -58,6 +59,13 @@ func GetReleaseByTag(ctx *context.APIContext) {
 		return
 	}
 
+	if release.IsDraft { // only the users with write access can see draft releases
+		if !ctx.IsSigned || !ctx.Repo.CanWrite(unit_model.TypeReleases) {
+			ctx.APIErrorNotFound()
+			return
+		}
+	}
+
 	if err = release.LoadAttributes(ctx); err != nil {
 		ctx.APIErrorInternal(err)
 		return