Fix remaining TypeScript errors and unable strict: true

[codykaup]

This is a continuation from #1070 by cleaning up the remaining errors and finally enabling strictness in our tsconfig.json! 🎉

I tried to make these changes as small as possible to not change the flow but some of the errors made that difficult. In theory, a good chunk of these rely on values existing despite the Context type having them as optional so throwing new errors when they don't exist shouldn't do anything in practice.

📦 Published PR as canary version: 11.11.1--canary.1072.11163487586.0

✨ Test out this PR locally via:

npm install chromatic@11.11.1--canary.1072.11163487586.0
# or 
yarn add chromatic@11.11.1--canary.1072.11163487586.0

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.12% (target: -1.00%)	❌ 69.12% (target: 80.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (c7a3f96)	8501	4580	53.88%
Head commit (b1f68c5)	8606 (+105)	4647 (+67)	54.00% (+0.12%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#1072)	217	150	69.12%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[github-actions]

📦 Package Size: 4644 KB
✅ Compared to main: 0 KB c7a3f96 (4644 KB)