feat(taxes): Add tax resources

[vincent-pochet]

Roadmap Task

👉 https://getlago.canny.io/feature-requests/p/create-several-tax-rates

Context

Currently, tax can be set individually either on the customer or the organization level. However, it’s not possible to define a global tax tag that can be reusable everywhere.

Description

The goal of this PR is to add:

• The Tax object
• The relation between taxes and organization
• The relation between taxes and customers
• The relation between taxes and invoices
• The relation between taxes and fees
• The relation between taxes and credit notes