perf(PageWrapper): fix the height calculation problem when footer and global footer are opened at the same time (#760)

* perf(PageWrapper): 优化PageWrapper在page的footer与全局页脚同时开启时的高度计算表现。

* docs(PageWrapper): 修复footer与全局页脚同时开启时的高度计算问题

Co-authored-by: NorthLan <lan6995@gmail.com>