Template "css-module-scope" attribute

[Lutymane]

Allow specifying CSS module component scope in <template> attribute.

Example

Before:

<template lang="pug">
.CTable__table
  .CTable__row
    .CTable__column
    .CTable__column
      .item
</template>

After:

<template lang="pug" css-module-scope="CTable">
.table
  .row
    .column
    .column
      .self__item
</template>

Allow using self__ special scope to refer to own component classes.

For nested paths, scope works the same: css-module-scope="VHome_Header".

Motivation:

Some components can consist of (mostly) shared classes only, so this feature will enhance code readability and DX drastically.