NocoBase v1.6.11: Optimize 502 error message

[client]
- Optimize 502 error message (#6547) by @chenos
- Only support plain text file to preview (#6563) by @mytharcher
[Collection field: Sequence] support setting sequence as the title field for calendar block (#6562) by @katherinehhh
[Workflow: Approval] Support to skip validator in settings by @mytharcher

[client]
- issue with date field display in data scope filtering (#6564) by @katherinehhh
- The ‘Ellipsis overflow content’ option requires a page refresh for the toggle state to take effect (#6520) by @zhangzhonghe
- Unable to open another modal within a modal (#6535) by @zhangzhonghe
[API documentation] API document page cannot scroll (#6566) by @zhangzhonghe
[Workflow] Make sure workflow key is generated before save (#6567) by @mytharcher
[Workflow: Post-action event] Multiple records in bulk action should trigger multiple times (#6559) by @mytharcher
[Authentication] Localization issue for fields of sign up page (#6556) by @2013xile
[Public forms] issue with public form page title displaying ‘Loading…’ (#6569) by @katherinehhh