Add missing tabs to org projects page (#22705) (#23412)

Backport #22705 by @yp05327

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.

Co-authored-by: yp05327 <576951401@qq.com>

routers/web/org/projects.go

@@ -123,6 +123,7 @@ func NewProject(ctx *context.Context) {
 	ctx.Data["Title"] = ctx.Tr("repo.projects.new")
 	ctx.Data["BoardTypes"] = project_model.GetBoardConfig()
 	ctx.Data["CanWriteProjects"] = canWriteProjects(ctx)
+	ctx.Data["PageIsViewProjects"] = true
 	ctx.Data["HomeLink"] = ctx.ContextUser.HomeLink()
 	shared_user.RenderUserHeader(ctx)
 	ctx.HTML(http.StatusOK, tplProjectsNew)