[feat]: add option to use a gradient or semi-transparent colours as the cell background

[maxim-petlyuk]

[#37]

Add the opportunity to use gradient and semi-transparent colors for cell background

Breaking change:
we have to make surface color as transparent to prevent impact on child composable's color

Surface(
        ...
        color = Color.Transparent,
        contentColor = Color.Unspecified,
        ...
)

How it looks in the code?

1. If you want to use gradient as a cell background..

OhTeePeeCellConfiguration.withDefaults(
        ...
        cellBackground = OhTeePeeCellBackground.Gradient(
            brush = Brush.linearGradient(
                colors = listOf(Color(0xFFAB5EEE), Color(0xFF4F0995)),
                start = Offset.Zero,
                end = Offset.Infinite,
            ),
            alpha = 0.62f
       )
        ...
)

2. If you want to use a single color as a cell background

OhTeePeeCellConfiguration.withDefaults(
        ...
        cellBackground = OhTeePeeCellBackground.Solid(backgroundColor.copy(alpha = 0.6f))
        ...
)

Reference how it may look with gradient colors: