Correctly check if the TextBox is PasswordBox before obscuring text

[Youssef1313]

GitHub Issue (If applicable): Addresses regression introduced in #6768, and also fixes the implementation of the same PR

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

• TextBox was incorrectly obscuring text.
• PasswordBox wasn't correctly accounting for programmatically changes of reveal mode

What is the new behavior?

Fix both problems.

PR Checklist

Please check if your PR fulfills the following requirements:

• Docs have been added/updated which fit documentation template (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Validated PR Screenshots Compare Test Run results.
• Contains NO breaking changes
• Associated with an issue (GitHub or internal) and uses the automatic close keywords.
• Commits must be following the Conventional Commits specification.

Other information

Internal Issue (If applicable):

[gitpod-io]