Add support for show-zero-points-immediately

[mikaelGusse]

Description

What?

Add support to rst-tools to enable the show-zero-points-immediately flag for an exercise.

Why?

Was asked by the teachers. Needs the requisite A+ pull request to function correctly A+ pr #1389

How?

Changed revealrule.py parsing

Testing

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• Accessibility test using the WAVE extension.
• Django unit tests.
• Selenium tests.
• Other test. (Add a description below)
• Manual testing.

[ADD A DESCRIPTION ABOUT WHAT YOU TESTED MANUALLY]

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• Firefox
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Think of what is affected by these changes and could become broken

Translation

• Did you modify or add new strings in the user interface? (Read about how to create translation)

Programming style

• Did you follow our style guides?
• Did you use Python type hinting in all functions that you added or edited? (type hints for function parameters and return values)

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• documents inside the doc directory.
• README.md.
• Aplus Manual.
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Is it Done?

• Reviewer has finished the code review
• After the review, the developer has made changes accordingly
• Customer/Teacher has accepted the implementation of the feature

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[ihalaij1]

I don't know how I feel about this syntax with a : to split the option arguments.
What do you think @murhum1 ?

Should we just have a separate option, e.g., :reveal-zero-points-immediately: that gives a warning if the :reveal-submission-feedback: option is missing?

There is a somewhat similar validation with :randomized: and :structured-randomized: options, where the build fails if both are used at the same time:

a-plus-rst-tools/directives/questionnaire.py

Lines 514 to 520 in 678f313

	if 'randomized' in self.options:
	if 'structured-randomized' in self.options:
	source, line = self.state_machine.get_source_and_line(self.lineno)
	raise SphinxError(
	source + ": line " + str(line) +
	"\nThe option 'randomized' can not be used together with the option 'structured-randomized'!"
	)