fix(react19): Allow null in most RefObjects

[scttcper]

In react 19 Ref types are made a bit more strict:

• Requires first argument in useRef(null)
• Wants void or undefined to be returned from ref callback instead of null
• Stricter type checks when passing down refs to props

part of https://github.com/getsentry/frontend-tsc/issues/68

trying to fix the various type errors when updating to react 19 https://github.com/getsentry/getsentry/actions/runs/13779044085/job/38533796056

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
9693	1	9692	4

View the top 1 failed test(s) by shortest run time

Dashboards > Detail prebuilt dashboards assigns unique IDs to all widgets so grid keys are unique

Stack Traces | 1.43s run time

Error: Unable to find an element with the text: Default Widget 1. This could be because the text is broken up by multiple elements. In this case, you can provide a function for your text matcher to make your matcher more flexible.

Ignored nodes: comments, script, style
...
    at waitForWrapper (.../sentry/sentry/node_modules/@.../dom/dist/wait-for.js:163:27)
    at .../sentry/sentry/node_modules/@.../dom/dist/query-helpers.js:86:33
    at Object.<anonymous> (.../views/dashboards/detail.spec.tsx:191:48)
    at Promise.then.completed (.../sentry/sentry/node_modules/jest-circus/build/utils.js:298:28)
    at new Promise (<anonymous>)
    at callAsyncCircusFn (.../sentry/sentry/node_modules/jest-circus/build/utils.js:231:10)
    at _callCircusTest (.../sentry/sentry/node_modules/jest-circus/build/run.js:316:40)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at _runTest (.../sentry/sentry/node_modules/jest-circus/build/run.js:252:3)
    at _runTestsForDescribeBlock (.../sentry/sentry/node_modules/jest-circus/build/run.js:126:9)
    at _runTestsForDescribeBlock (.../sentry/sentry/node_modules/jest-circus/build/run.js:121:9)
    at _runTestsForDescribeBlock (.../sentry/sentry/node_modules/jest-circus/build/run.js:121:9)
    at run (.../sentry/sentry/node_modules/jest-circus/build/run.js:71:3)
    at runAndTransformResultsToJestFormat (.../sentry/sentry/node_modules/jest-circus/build/legacy-code-todo-rewrite/jestAdapterInit.js:122:21)
    at jestAdapter (.../sentry/sentry/node_modules/jest-circus/build/legacy-code-todo-rewrite/jestAdapter.js:79:19)
    at runTestInternal (.../sentry/sentry/node_modules/jest-runner/build/runTest.js:367:16)
    at runTest (.../sentry/sentry/node_modules/jest-runner/build/runTest.js:444:34)
    at Object.worker (.../sentry/sentry/node_modules/jest-runner/build/testWorker.js:106:12)

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