[PS-1111] Added prefix "Vault:" for accessibility on vault selector items

[aj-rosado]

Type of change

- [ x ] Bug fix
- [ ] New feature development
- [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

Improve the accessibility message when selecting an item from the vault selector on Browser Extension

Code changes

• vault-select.component.html: Added accessibility attributes

Before you submit

- [x] I have checked for **linting** errors (`npm run lint`) (required)
- [ ] I have added **unit tests** where it makes sense to do so (encouraged but not required)
- [ ] This change requires a **documentation update** (notify the documentation team)
- [ ] This change has particular **deployment requirements** (notify the DevOps team)

[dgoodman-bw]

Although not mentioned in the ticket, would there be value in applying the same or similar fix to the vault selector items in the other client apps (desktop and web) as well?

[patrickhlauke]

Closes one aspect of https://github.com/bitwarden/clients/issues/3078