Add Cell Phone, Default Time Zone and State Abbreviation translation for en-PAK locale

[wonderer007]

Motivation / Background

en-PAK locale missing cell phone format. The existing Faker::PhoneNumber.phone_number generator mixes both landline and mobile (even though that too is wrong per Pakistan format). This PR adds cell phone format for the en-PAK locale.

It also includes state abbreviations and default time zones.

Additional information

1. https://en.wikipedia.org/wiki/Abbreviations_of_administrative_units_of_Pakistan
2. https://en.wikipedia.org/wiki/List_of_telecommunication_companies_in_Pakistan

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug, refactor something, or add a feature.
• Tests and Rubocop are passing before submitting your proposed changes.

If you're proposing a new generator or locale:

• Double-check the existing generators documentation to make sure the new generator you want to add doesn't already exist.
• You've reviewed and followed the Contributing guidelines.

[wonderer007]

Here is the output that I have now in the console:

3.2.2 :021 > Faker::Config.locale = 'en-PAK'
 => "en-PAK" 
3.2.2 :022 > Faker::PhoneNumber.cell_phone
 => "0321-5631055" 
3.2.2 :023 > Faker::PhoneNumber.cell_phone
 => "0346-6844205" 
3.2.2 :024 > Faker::PhoneNumber.cell_phone
 => "0301-8081558" 
3.2.2 :025 > Faker::Address.default_time_zone
 => "Asia/Karachi" 
3.2.2 :026 > Faker::Address.state_abbr
 => "PK-JK" 
3.2.2 :027 > Faker::Address.state_abbr
 => "PK-SD" 
3.2.2 :028 > Faker::Address.state_abbr
 => "PK-TA"