Upgrade TypeScript from 4.5 to 4.8

[aduth]

Why: Take advantage of the latest features and bug fixes.

Errors addressed after upgrade:

$ tsc
app/javascript/packages/normalize-yaml/index.js:20:29 - error TS2463: A binding pattern parameter cannot be optional in an implementation signature.

20 function normalize(content, { prettierConfig, exclude } = {}) {
                               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

app/javascript/packages/secret-session-storage/index.ts:110:30 - error TS2345: Argument of type 'ArrayBuffer' is not assignable to parameter of type 'Uint8Array'.
  Type 'ArrayBuffer' is missing the following properties from type 'Uint8Array': BYTES_PER_ELEMENT, buffer, byteOffset, copyWithin, and 24 more.

110       return JSON.parse(ab2s(data));
                                 ~~~~

app/javascript/packages/secret-session-storage/index.ts:125:84 - error TS2345: Argument of type '(buffer: Uint8Array) => any' is not assignable to parameter of type '(value: ArrayBuffer, index: number, array: ArrayBuffer[]) => any'.
  Types of parameters 'buffer' and 'value' are incompatible.
    Type 'ArrayBuffer' is not assignable to type 'Uint8Array'.

125     sessionStorage.setItem(this.storageKey, JSON.stringify([encryptedData, iv].map(ab2s)));
                                                                                       ~~~~

app/javascript/packages/verify-flow/context/flow-context.tsx:27:31 - error TS2842: 'string' is an unused renaming of 'completionURL'. Did you intend to use it as a type annotation?

27   onComplete({ completionURL: string }): void;
                                 ~~~~~~

  app/javascript/packages/verify-flow/context/flow-context.tsx:27:39
    27   onComplete({ completionURL: string }): void;
                                             ~
    We can only write a type for 'completionURL' by adding a type for the entire parameter here.

app/javascript/packs/document-capture.jsx:130:7 - error TS2322: Type 'string[][]' is not assignable to type 'HeadersInit | undefined'.
  Type 'string[][]' is not assignable to type '[string, string][]'.
    Type 'string[]' is not assignable to type '[string, string]'.
      Target requires 2 element(s) but source may have fewer.

130       headers: /** @type {string[][]} */ ([csrf && ['X-CSRF-Token', csrf]].filter(Boolean)),
          ~~~~~~~

[aduth]

I snuck in a TypeScript file conversion as part of the pull request, but this line was the only change needed to satisfy the new errors. See the original commit 935b91d to see the change more clearly.

[aduth]

Nice thing about native TypeScript is that the unused values are flagged, unlike JSDoc-based types.

[zachmargolis]

LGTM