IA-3711: add methods to test mixins

[quang-le]

What problem is this PR solving? Explain here in one sentence.

Related JIRA tickets : IA-3711

Self proofreading checklist

• Did I use eslint and black formatters
• Is my code clear enough and well documented
• Are my typescript files well typed
• New translations have been added or updated if new strings have been introduced in the frontend
• My migrations file are included
• Are there enough tests
• Documentation has been included (for new feature)

Doc

Tell us where the doc can be found (docs folder, wiki, in the code...).

Changes

• add PolioTestCaseMixin+method to create campaign test data
• add method to add base test data: account, source, user

How to test

Try to write/refactor tests using the methods/mixins

Print screen / video

NA

Notes

These changes have been cherry-picked from https://github.com/BLSQ/iaso/pull/1801/commits, but I spun a PR so it could be used faster by everyone

Follow the Conventional Commits specification

The merge message of a pull request must follow the Conventional Commits specification.

This convention helps to automatically generate release notes.

Use lowercase for consistency.

Example:

fix: empty instance pop up

Refs: IA-3665

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[mathvdh]

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