Add BorderTitle to Style

[davidmdm]

Related to #87

This adds a new Style API: BorderTitle(title string).

It is very limited in that it only sets a title on the top border and aligned to the left.
It only adds the title if the title fits otherwise it is ignored.

It could be more configurable but this should cover most needs.

For example:

lipgloss.NewStyle().
	Width(10).
	Height(4).
	Border(NormalBorder()).
	BorderTitle("Test").
	Render()

Would render:

┌─ Test ───┐
│          │
│          │
│          │
│          │
└──────────┘

[davidmdm]

@meowgorithm @aymanbagabas

Pinging for review ❤️

[davidmdm]

Pushed commit to fix the linting issue and to rename the commit message to use conventional commit style.

[davidmdm]

Also including a screenshot of what this looks like in a personal project of mine: