Build: Migrate @storybook/html-vite to strict TS

[usrrname]

What I did

Part of #22176 migration to type-strictness for @storybook/html-vite:

1. Change in tsconfig.json "strict": false -> "strict": true
2. Run yarn check in the directory of the package.
3. Fix all TS errors.

How to test

0. run yarn task --task compile --no-link --start-from=install
1. cd into code/frameworks/html-vite
   2.yarn check from project root
2. Run yarn task --task dev --template html-vite/default-ts --start-from=auto to check everything still builds in sandbox
3. Run e2e tests against dev sandbox yarn task --task e2e-tests-dev --template html-vite/default-ts
4. Run yarn run test from root of codebase
5. Run yarn run test:ci from root of codebase, drum fingers.... and wait for checking validity types nx run @storybook/html-vite:check to succeed.

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes -- n/a
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]

[kasperpeulen]

LGTM and thanks!