Add missing tabs to org projects page (#22705)

Fixes https://github.com/go-gitea/gitea/issues/22676

Context Data `IsOrganizationMember` and `IsOrganizationOwner` is used to
control the visibility of `people` and `team` tab.

2871ea0809/templates/org/menu.tmpl (L19-L40)

And because of the reuse of user projects page, User Context is changed
to Organization Context. But the value of `IsOrganizationMember` and
`IsOrganizationOwner` are not being given.

I reused func `HandleOrgAssignment` to add them to the ctx, but may have
some unnecessary variables, idk whether it is ok.

I found there is a missing `PageIsViewProjects` at create project page.

routers/web/shared/user/header.go

@@ -9,6 +9,8 @@ import (
 )
 
 func RenderUserHeader(ctx *context.Context) {
+	ctx.Data["IsProjectEnabled"] = true
+	ctx.Data["IsPackageEnabled"] = setting.Packages.Enabled
 	ctx.Data["IsRepoIndexerEnabled"] = setting.Indexer.RepoIndexerEnabled
 	ctx.Data["ContextUser"] = ctx.ContextUser
 }