Offer TypeScript format functions

[json-derulo]

Description
Angular offers TypeScript functions to make the logic of their i18n pipes available also in TypeScript code, i.e. the formatDate() function. It would be useful to have such functions available also for the pipes in this package.

Proposed Solution
For each pipe, there is a TypeScript function exposed, which performs the base logic of the pipe, i.e. intlFormatDate().

Alternatives considered
There might be workarounds like constructing or injecting the pipe, but this is not good practice and could cause issues.