pgAdmin 4: A user's other sessions survive a change of their password

pgAdmin 4 did not invalidate a user's existing sessions when their password changed, either through the user's own change password dialog or through an administrator resetting it in User Management. A session established before the change, for example on another device or by someone who had obtained the old password or a session cookie, therefore stayed logged in after the change, which is the step a user or administrator takes precisely to cut such access off. It remained usable until it expired. The fix rotates the user's session identifier (fs_uniquifier) whenever the password is changed, so every other session of that user is logged out. The session that made the change is logged in again and keeps its database connections. Saved server passwords, including those for shared servers, are re-encrypted under the new key; any that cannot be decrypted are cleared and the user is told. If re-encryption fails, the sessions are still revoked and the saved passwords are cleared rather than the change failing. This issue affects pgAdmin 4: before 9.19.