fix: list sharers with the same display name separately in the Shared By filter - #4152

Description

The "Shared By" filter in Shared with me now lists every sharer, even when two people have the same display name, so each of them can be selected.

Related Issue

• Fixes Shared By filter merges sharers with the same display name #4147

How Has This Been Tested?

• test environment: unit tests (Vitest), browser tests (Playwright) against a local OpenCloud
• test case 1: unit: filter items are deduplicated by id, so same-name sharers stay separate
• test case 2: browser: two sharers named "Twin" both listed and selectable on desktop and Pixel 7, combined selection, reload; regular sharers still listed once, clear filter

Types of changes

• Bugfix
• Enhancement (a change that doesn't break existing code or deployments)
• Breaking change (a modification that affects current functionality)
• Technical debt (addressing code that needs refactoring or improvements)
• Tests (adding or improving tests)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)