[PM-15200] first pass at "generated credential" screen reader notifications

[audreyality]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-15200

📔 Objective

Notify users with screen readers when a new credential is generated.

📸 Screenshots

N/A

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – ffb4e5eb-c74e-4862-982c-92fdebcb72d7

Fixed Issues (2)

Great job! The following issues were fixed in this Pull Request

Severity	Issue	Source File / Package
	Client_Privacy_Violation	/bitwarden_license/bit-web/src/app/tools/access-intelligence/org-at-risk-members-dialog.component.html: 15
	Client_Privacy_Violation	/libs/tools/generator/components/src/username-generator.component.html: 3

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 34.45%. Comparing base (70cf459) to head (7023e0a).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12877   +/-   ##
=======================================
  Coverage   34.44%   34.45%           
=======================================
  Files        2974     2974           
  Lines       90667    90667           
  Branches    16989    16989           
=======================================
+ Hits        31233    31240    +7     
+ Misses      56968    56961    -7     
  Partials     2466     2466           

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