Feature request: Filter out 'shadowing' errors, for the humans

Hi there 👋. Awesome repo you've got here!

We at the [stryker mutation testing](https://stryker-mutator.io) team have been looking into validation with ajv. We've come to the same conclusion, error messages directly from AJV are not really designed for humans. We're thinking of using better-ajv-errors.

However, we're also thinking of filtering out what I call 'shadowing' errors.

A shadowing error is an error that results logically from another error. Some examples:

```js
[
{ // This is a useless error for a human
keyword: 'type',
dataPath: '.mutator',
params: { type: 'string' },
// [...]
},
{ // => This is the most specific error. This is for humans!
keyword: 'required',
dataPath: '.mutator',
params: { missingProperty: 'name' },
// [...]
},
{ // This is a useless error for a human
keyword: 'oneOf',
dataPath: '.mutator',
params: { passingSchemas: null },
[...]
}
]
```

Or:

```js
[
{ // This is a useless error for a human
keyword: 'type',
dataPath: '.logLevel',
params: { type: 'string' },
// [...]
},
{ // => This is the most specific error. This is for humans!
keyword: 'enum',
dataPath: '.logLevel',
params: { allowedValues: ['info', 'warn'] },
// [...]
},
]
```

A first draft of the filtering is created here:

https://github.com/stryker-mutator/stryker/blob/627d2f7e403042845bcece73c838c9447bbf522c/packages/core/src/config/validationErrors.ts#L55-L74

Do you think this filtering is useful for other projects as well? Should it be added to better-ajv-errors? Maybe as an option? Or do you want to keep it separate?

I would be willing to prepare it in a PR if you agree that this is a feature useful for all humans, nut just mutant-killing humans 😉.

Review the shadowing-error examples in this issue and the linked Stryker draft at packages/core/src/config/validationErrors.ts#L55-L74. First establish the intended filtering rules and whether they belong in better-ajv-errors or remain separate; done requires an agreed feature scope and option behavior, followed by validation against the shown AJV errors.

Written by the indexing model from the issue text.