Add support for customizing Tab field label

[jure123]

Currently I guess there is no way to customize label in Tabs field. For example, we want to put an array field inside one tab, and we want to show a dynamic tab label, like "News [number of array items]".

Tab field currently has admin.components. Cell config property, but setting this to a custom component does not have any effect. Source code for Tab component does not include rendering of any custom components around the label:
https://github.com/payloadcms/payload/blob/main/packages/ui/src/fields/Tabs/Tab/index.tsx