Fix #5171: Fixes all warnings in "Accessibility" category

[theMr17]

Explanation

Fixes #5171

Under this category, the warnings are mainly of 3 types:

1. Warning: Image without contentDescription.
   Fix: Add a contentDescription to each of those ImageView, or mark as not important for accessibility.

2. Warning: 'onTouch' lambda should call 'View#performClick' when a click is detected
   Fix: Call customView.performClick( ).

3. Warning: 'clickable' attribute found, please also add 'focusable'.
   Fix: Set android:focusable="true" as its necessary if android:clickable="true".

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

If your PR includes UI-related changes, then:

• Add screenshots for portrait/landscape for both a tablet & phone of the before & after UI changes
• For the screenshots above, include both English and pseudo-localized (RTL) screenshots (see RTL guide)
• Add a video showing the full UX flow with a screen reader enabled (see accessibility guide)
• Add a screenshot demonstrating that you ran affected Espresso tests locally & that they're passing

[adhiamboperes]

Thanks @theMr17! I have left some suggestions, and once done please attach a screenshot that shows running ./gradlew :app:lint does not raise any of these 3 warnings.

[oppiabot]

Unassigning @adhiamboperes since the review is done.

[oppiabot]

Hi @theMr17, it looks like some changes were requested on this pull request by @adhiamboperes. PTAL. Thanks!

[theMr17]

@adhiamboperes PTAL, I have done the changes you suggested. Also, here is the screenshot that shows those 3 warnings are not present anymore.

[oppiabot]

Unassigning @theMr17 since a re-review was requested. @theMr17, please make sure you have addressed all review comments. Thanks!

[adhiamboperes]

Thanks @theMr17, this LGTM!

[oppiabot]

Unassigning @adhiamboperes since they have already approved the PR.

[oppiabot]

Hi @theMr17, this PR is ready to be merged. Please address any remaining comments prior to merging, and feel free to ask someone to merge your PR once the CI checks pass and you're happy with it. Thanks!