Better types for TargetArch and TargetPlatform

[RareScrap]

Preflight Checklist

• [x] I have read the contribution documentation for this project.
• [x] I agree to follow the code of conduct that this project follows, as appropriate.
• [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

TypeScript compiler can't validate string literals for TargetArch and TargetPlatform types:

import { HookFunction, HookFunctionErrorCallback, OfficialArch, OfficialPlatform, TargetArch, TargetPlatform } from '@electron/packager';
// ...

const hookFunctionExample: HookFunction = (buildPath: string, electronVersion: string, platform: TargetPlatform, arch: TargetArch, callback: HookFunctionErrorCallback) => {
    const something1: TargetArch = "foo" // will compile, but obviously incorrect
    const something2: TargetPlatform = "Шind0wz 123" // will compile, but obviously incorrect

    const something3: OfficialArch = "foo" // will not compile, but distincts from the `arch` parameter's type
    const something4: OfficialPlatform = "Шind0wz 123" // will not compile, but distincts from the `platform` parameter's type

    // ...
}

// ...

That's because the TypeScript compiler expands these types to any value string (source link):

// From now TargetArch and TargetPlatform are basically unconstrained string type aliases
export type TargetArch = OfficialArch | string;
export type TargetPlatform = OfficialPlatform | string;

Proposed Solution

I see several possible solutions:

1. Remove TargetArch and TargetPlatform in flavor of OfficialArch and OfficialPlatform respectively
   1. Or at least do it in HookFunction signature
2. Remove | string type expansion from TargetArch and TargetPlatform

I'm not sure what is the semantic difference between OfficialArch and TargetArch types so a clarification from Electron Packager devs is required to choose the best solution

Alternatives Considered

None

Additional Information

None

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