Scope exports from Grapher util

[handeyeco]

Summary:

Several things in grapher/util.ts were exported out of perseus, but were only used within perseus.

Test plan:

Nothing should change

[khan-actions-bot]

Gerald

Required Reviewers

• @Khan/perseus for changes to .changeset/rich-lizards-rule.md, packages/perseus/src/index.ts, packages/perseus-editor/src/widgets/grapher-editor.tsx, packages/perseus/src/widgets/grapher/util.tsx

---

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[github-actions]

npm Snapshot: Published

Good news!! We've packaged up the latest commit from this PR (d4615b0) and published it to npm. You
can install it using the tag PR1806.

Example:

yarn add @khanacademy/perseus@PR1806

If you are working in Khan Academy's webapp, you can run:

./dev/tools/bump_perseus_version.sh -t PR1806

[github-actions]

Size Change: -65 B (-0.01%)

Total Size: 866 kB

Filename	Size	Change
packages/perseus-editor/dist/es/index.js	280 kB	+19 B (+0.01%)
packages/perseus/dist/es/index.js	419 kB	-84 B (-0.02%)

ℹ️ View Unchanged

Filename	Size
packages/kas/dist/es/index.js	38.8 kB
packages/keypad-context/dist/es/index.js	760 B
packages/kmath/dist/es/index.js	4.27 kB
packages/math-input/dist/es/index.js	77.8 kB
packages/math-input/dist/es/strings.js	1.79 kB
packages/perseus-core/dist/es/index.js	1.48 kB
packages/perseus-linter/dist/es/index.js	22.2 kB
packages/perseus/dist/es/strings.js	3.4 kB
packages/pure-markdown/dist/es/index.js	3.66 kB
packages/simple-markdown/dist/es/index.js	12.4 kB

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