Improve Internationalization linting rules

[pavish]

Description

We need to improve linting for i18n for better maintenance. Following are the rules we need to implement:

• Essential:
  • Add lint rule to identify strings in dict file that are no longer used in app
  • Add lint rule to check if all translations used in app are present in dict file
  • Add lint rule to make sure that components within '/src/component-library' are not translated using svelte-i18n
  • Add lint rule to ensure the format is inline with the Transifex JSON with ICU plurals format
• Good to have:
  • Add rule to ensure all i18n translation function calls have the required variables
  • Add rule to ensure plurals (dict and function calls) have the required variables and syntax