Fix #4641, #4674, #4579, #4591: Assorted beta fixes

[BenHenning]

Explanation

Fixes #4641
Fixes #4674
Fixes #4579
Fixes #4591

Miscellaneous fixes for Beta MR2. Specifically:

• Terms of Use needs updating #4641 is addressed by updating the terms of service wording. No test is needed here since manual verification is sufficient.
• Hide all downloads options behind downloads flag #4674 is addressed by replacing the existing automatic topic updates platform with a generic "all downloads" one (which will be used for all downloads gating moving forward). Admin controls, add profile, and profile edit pages have been updated to only show downloads-related settings if this flag is enabled. Corresponding tests have been updated. FAQ question 8 was also removed since it asks about how to download lessons, and this support isn't in the app yet. Some strings referencing downloads have also been updated.
• The home screen is blank on opening beta app #4579 is addressed by properly handling the case where unpublish topics with previous progress would cause the topic list to fail to load. A test was added to verify the fix, but it required a new FakeAssetRepository to be introduced.
• Incorrect answer responses are not displayed for a question in Mixed numbers and the Number Line 1 #4591 is addressed by fixing FractionInputHasIntegerPartEqualToRuleClassifierProvider's input type (which should be SIGNED_INT but was incorrectly NON_NEGATIVE_INT before; this seems to have been wrong since the classifier was introduced).

Test exemption: FakeAssetRepository doesn't have a test added since it uses a real production AssetRepository, and tests don't yet exist for that). They ought to be tested together.

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

For UI-specific PRs only

Screenshots showing the before & after changes due to hiding downloads options:

	Without changes	With changes
Profile creation
Profile edit
Admin controls

Espresso test rules for affected UI tests:

Affected Test	Test Results
AdministratorControlsActivityTest	(Skipped since there are tablet tests to also run, so the suite won't actually pass cleanly)
ProfileEditActivityTest	(Same as above)
AdministratorControlsFragmentTest
ProfileEditFragmentTest

New Robolectric tests failing for corresponding regressions:

Issue	Test Suite	Failure Specifics	Failure Results
#4579	TopicListControllerTest	1/36 tests fail
#4591	FractionInputHasIntegerPartEqualToRuleClassifierProviderTest	22/23 tests fail

Missing artifacts:

• Accessibility: not particularly relevant to these changes since the user-facing changes are either crash fixes or removing UI elements (except in the case of terms of service, but that doesn't require additional a11y testing coverage or demonstration here).
• RTL: nothing in this change affects RTL specifically.
• Landscape: since the main UI changes are removing elements, the changes to tablet aren't very "interesting" to show off.
• Tablet: same rationale as for landscape.
• Internationalization: same rationale as RTL.

[BenHenning]

The changes are fairly self explanatory, I think, but I'll follow up with a clearer description & tests in the next 1-2 days.

[BenHenning]

@seanlip PTAL. As an FYI I have also self-reviewed the whole PR.

[seanlip]

Thanks, took a pass. No concerns.

[oppiabot]

Assigning @rt4914 for code owner reviews. Thanks!

[BenHenning]

Thanks @seanlip! Going ahead and merging this without @rt4914’s approval since it’s release blocking.