Add masked property while rendering text-(like) objects

[sudipghimire533]

Description

This PR will enable to have a text object which hides the actual content. This will be specifically useful to show sensative content like password in tui but being still able to access the value, but without rendering it

Testing guidelines

Create a Span through Span::masked method, and such widget should be rendered as masked character as specified

Checklist

• [X] I have read the contributing guidelines.
• [X] I have added relevant tests.
• [X] I have documented all new additions.