Create textarea as separate block (close #1033)

I've made only basics yet: `common`+`desktop`, `BEMHTML`-templates, js, styles only for `islands` theme.
I didn't remove `input_type_textarea` to have ability to compare new block with it.
Не надо обращаться к полю blockMods, оно внутреннее.
`ctx.mod('disabled') && (attrs.disabled = 'disabled')`