Fixes #3179: Optimised reading_text_size_fragment implementation

[bhaktideshmukh]

Explanation

Fixes #3179

• Shifted reading_list_app_bar_layout from mobile xml files to the reading_text_size_activity.
• Deleted layout-sw600dp/reading_text_size_fragment file.

Screeshots

Phone portrait mode

Before	After

Phone landscape mode

Before	After

Tablet portrait mode

Before	After

Tablet landscape mode

Before	After

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).
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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

[oppiabot]

Hi @bhaktideshmukh, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[bhaktideshmukh]

@rt4914
Gentle reminder to review this PR.
Thanks.

[rt4914]

@bhaktideshmukh Please add tablet screenshots too even if they are part of fragment.

[rt4914]

@bhaktideshmukh PTAL

[bhaktideshmukh]

@bhaktideshmukh Please add tablet screenshots too even if they are part of fragment.

Done

[BenHenning]

Apologies. I will need to look at this tomorrow.

[rt4914]

@bhaktideshmukh just minor change

[rt4914]

LGTM