Update mailbox button text from "Edit name" to "Rename" (#9108)

[Jijo07]

Changes Made

• Updated the mailbox button text from "Edit name" to "Rename" as requested in issue #9108.

Fixes #9108

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[ChristophWurst]

@nimishavijay I hope https://github.com/nextcloud/mail/issues/9108 is fine with you :)

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[ChristophWurst]

Resubmit as https://github.com/nextcloud/mail/pull/9791