Add validation for Botswana TIN

[unho]

• https://www.rsm.global/botswana/news/new-burs-online-system-lekgetho suggests it is named Tax Identification Number (TIN)
• https://www.ey.com/Publication/vwLUAssets/Botswana_Tax_Authority_introduces_E_service/$FILE/2014G_CM4342_Indirect_Botswana%20Tax%20Authority%20introduces%20E-service.pdf
• http://world.salestaxhandbook.com/bw-botswana

  The VAT number format is: C01234567890 for companies. I01234567890 for individuals P01234567890 for partnerships T01234567890 for trusts

• https://www.burs.org.bw/index.php/tax/registration suggests that its name is Income Tax TIN.
• According to https://www.stanbicbank.co.bw/static_file/zimbabwe/Business/File%20Downloads/Business%20Account%20Opening%20Form.pdf seems to be named Tax Identification Number (TIN)
• calls it BURS TIN (BURS being Botswana Unified Revenue Service)
• According to http://brandbotswana.co.bw/wp-content/uploads/2020/09/Botswana-BITC-Investor-Handbook.pdf seems to be called Tax Identification Number
• According to https://www.bitc.co.bw/tax-registration seems to be called Tax Identification Number (TIN)
• It also looks like there are other numbers: https://www.grantthornton.co.bw/globalassets/1.-member-firms/botswana/insights_pdfs/cs_alerts/2021-06-04-tax-alert-4-of-2021.pdf
  • Only 2 examples were found while searching for TIN, but UIN (Unique Identification Number) has more examples online, and there is a search tool for UIN https://www.cipa.co.bw/ng-cipa-master/ui/XP-LQoH2RI6kdF1KB0vDQG2phCQRjr7CsEX-HyqgWw-76dMAY6Q_iUfM00vcbN4klW3DqrCuCoVpK6ygG6Z9jOJuT6xYiDtFYH9rFjj-QTdyKY-SS

Examples:

• All that could be found by searching for variations of TIN:
  • C475463-01-01-3 from https://kad.co.bw/wp-content/uploads/2021/01/KAD-BURS-VAT-Reg-Lettter.pdf
  • C 480779-01-01-4 from https://molexengineeringtech.co.bw/index.php/component/bdthemes_shortcodes/?view=download&id=07d6615ed1db58cb99006b63a74566
  • C28820701017
• Found as VAT/Vat No/VAT number:
  • C0405090112 from https://ishop.co.bw/
  • C132411011111 from https://bolengconsults.co.bw/
  • 33252101111 from https://www.envesys.co.bw/contacts/
  • C04348401112 from http://prostationers.co.bw/contact_us/
  • CO5660201112 from https://www.contemporarylinens.co.bw/
  • C008 0800 1111 from https://www.pulamed.co.bw/sites/default/files/documents/Pula_Med_Policy_Wording_0.pdf
  • C15573301112 from https://www.botswanatourism.co.bw/sites/default/files/2022-08/Exhibitors_Manual_2022_spread.pdf
  • CO4470201112 from https://speedtech.co.bw/brouchures/chs%2010.pdf
  • C08371001112 from http://paxus.co.bw/wp-content/uploads/2017/05/paxus-company-profile.pdf
  • C09564801113 from https://mds.co.bw/