Add more possibilities for ComposeView styling

[nlamah]

Describe the Feature This is a request to be able to style the compose view in the following ways:

• Add custom padding under the the composeView to the bottom of the screen
• Add possibility to hide the send button when it is disabled
• Add possibility to give a custom size the sendIcon

To Reproduce

Expected behaviour Add some properties to theParleyComposeViewAppearanceand apply it toParleyComposeView`

Screenshots