Implement workspace description editing functionality in Workspace List view
MR: Pending
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## Description
As part of our [new designs for Workspaces](https://gitlab.com/groups/gitlab-org/-/epics/18674), we need to implement the editing functionality for workspace descriptions so that users can update their workspace descriptions. As part of this issue we will need to update the `description` field created in https://gitlab.com/gitlab-org/gitlab/-/issues/562374+s by adding an edit link to the description section created in https://gitlab.com/gitlab-org/gitlab/-/issues/565047+s
## Acceptance criteria
- [ ] "Edit" link opens inline editing interface
- [ ] Save changes via `workspaceUpdate` GraphQL mutation to update workspace description
- [ ] Cancel functionality reverts to original description without saving
- [ ] Show loading state during save operation with disabled UI
- [ ] Display error messages for failed save operations
- [ ] When description is null/empty, show "Add description" link instead of "Edit"
- [ ] "Add description" opens same editing interface as "Edit"
- [ ] Validate description length according to backend field constraints
## TODO: Implementation plan
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issue