fix(locale) Add bulgarian localization

[pignatov]

Description

Add new bulgarian localization

Motivation and Context

New localization added to vuetify

How Has This Been Tested?

Tested some of the visual changes (data-table footer)

Markup:

// Paste your FULL Playground.vue here

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any features but makes things better)

Checklist:

• The PR title is no longer than 64 characters.
• The PR is submitted to the correct branch (master for bug fixes and documentation updates, dev for new features and backwards compatible changes and next for non-backwards compatible changes).
• My code follows the code style of this project.
• I've added relevant changes to the documentation (applies to new features and breaking changes in core library)

[jacekkarczmarczyk]

Please add a corresponding PR in vue-cli-plugins repo (see vuetifyjs/vue-cli-plugins#154 for example)

[pignatov]

Here is the PR in vue-cli-plugins - vuetifyjs/vue-cli-plugins#218