Add @typescript-eslint/explicit-member-accessibility

[chriszarate]

Add @typescript-eslint/explicit-member-accessibility rule to enforce the use of accessibility keywords like public, private, or protected. These keywords are critical to preventing the unintended exposure of private implementation details.

https://typescript-eslint.io/rules/explicit-member-accessibility/

// Good
class MyClass {
  private secretKey = 'foo';

  constructor( private anotherSecretKey: string ) {}

  private updateDBRecord() {}

  public createResource() {
    // do some validation
    this.updateDBRecord();
  }
}

// Bad
class MyClass {
  secretKey = 'foo';

  constructor( anotherSecretKey: string ) {
    this.anotherSecretKey = anotherSecretKey;
  }

  updateDBRecord() {}

  createResource() {
    // do some validation
    this.updateDBRecord();
  }
}

[sanmai]

I can't think of the downsides of this approach.