feat(fw-input): Added slots and modified styles for fw-input based on DSM

[kishore-kumar-E3682]

• changed the disabled background-color to #f7f9fa
• removed the bottom spacing on the input and increase the font-size to 14px
• reduced the size of the close icon to 8px
• changed the font-weight for the disabled state and placeholder
• exposed css variables to change the normal state font color of label and hint
• modified fw-input as a block element so that consuming component can add their margin or padding
• Added slots to create custom input as shown below

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My commits have standard messages as mentioned in Contributing Guidelines

How Has This Been Tested?

[sangeet-fw]

LGTM