Fix #3662: Complete lightweight checkpointing

[MaskedCarrot]

Explanation

Fixes #3662

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The PR follows the style guide.
• The PR does not contain any unnecessary auto-generated code from Android Studio.
• The PR is made from a branch that's not called "develop".
• The PR is made from a branch that is up-to-date with "develop".
• The PR's branch is based on "develop" and not on any other branch.
• The PR is assigned to an appropriate reviewer in both the Assignees and the Reviewers sections.

Final Result

lightweight_checkpointing.mp4

Espresso Tests

StateFragmentTest

ExplorationActivityTest

[BenHenning]

@MaskedCarrot per my earlier comment, this isn't yet based on develop with passing CI. Please reassign at that point.

[anandwana001]

Assign me back once test passes on CI.

Following on this, assign me back once this PR get develop branch as base branch.

[anandwana001]

Code owner file LGTM

[oppiabot]

Unassigning @anandwana001 since they have already approved the PR.

[oppiabot]

Assigning @vinitamurthi for code owner reviews. Thanks!

[vinitamurthi]

I think I was added by mistake, I dont codeown any of these files. Removing myself!

[BenHenning]

Thanks @MaskedCarrot. LGTM!

[BenHenning]

Given everyone's approved, CI is passing, and there are not outstanding conversation threads, merging this.