fix(ts-transformer): allow to override user defined message id via overrideIdFn as function

[nodkz]

We can define overrideIdFn as a function that receives msg.id as the first argument.
BUT according to current logic, this function will be never called. And users aren't able to modify already defined id. For example, I want to globally add prefixes to all ids. But cannot do it right now.
This PR fixes this issue.

So current logic will be:

• overrideIdFn is a string
  • if msg.id is defined leave it unchanged
  • if msg.id is empty then use interpolateName with provided template
• overrideIdFn is a function
  • pass msg.id to function as first arg. Allow to user decide what to do with id - it may be empty or contain already defined value

[nodkz]

For example, I'm using the following typescript plugin (it adds pkg. prefix to already defined ids OR generate pkg.[contenthash:6] if id is not provided):

// tsconfig.build.json
{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "plugins": [
      {
        "transform": "./transformers/react-intl.ts"
      }
    ]
  },
  "exclude": ["node_modules", "**/__tests__", "**/__mocks__"],
  "include": ["src/**/*", "types/types.d.ts"]
}

// ./transformers/react-intl.ts

import { transform, Opts, interpolateName } from '@formatjs/ts-transformer';

export default function intlTransform(opts: Opts) {
  return transform({
    extractFromFormatMessageCall: true,
    overrideIdFn: (
      existedId?: string,
      defaultMessage?: string,
      description?: string,
      filePath?: string
    ) => {
      let id;
      if (existedId) {
        id = existedId;
      } else {
        const content = description ? `${defaultMessage}#${description}` : defaultMessage;
        id = interpolateName({ sourcePath: filePath } as any, '[contenthash:6]', {
          content,
        });
      }
      return `pkg.${id}`;
    },
    onMsgExtracted: (file, msgs) => {
      console.log(msgs);
    },
    ...opts,
  });
}

[longlho]

you mind adding some tests for the new behavior?

[nodkz]

Closes due #1926