…ructures (elastic#72730)

###  Summary

The intent is to get the data structures in similar to rules so that we can have eventually immutable and versioned lists in later releases without too much hassle of upgrading the list and list item data structures.

* Adds version and immutability data structures to the exception lists and the value lists.
* Adds an optional version number to the update route of each so that you can modify the number either direction or you can omit it and it works like the detection rules where it will auto-increment the number.
* Does _not_ add a version and immutability to the exception list items and value list items.
* Does _not_ update the version number when you add a new exception list item or value list item. 

**Examples:**

❯ ./post_list.sh
```json
{
  "_version": "WzAsMV0=",
  "id": "ip_list",
  "created_at": "2020-07-21T20:31:11.679Z",
  "created_by": "yo",
  "description": "This list describes bad internet ip",
  "immutable": false,
  "name": "Simple list with an ip",
  "tie_breaker_id": "d6bd7552-84d1-4f95-88c4-cc504517b4e5",
  "type": "ip",
  "updated_at": "2020-07-21T20:31:11.679Z",
  "updated_by": "yo",
  "version": 1
}
```
❯ ./post_exception_list.sh
```json
{
  "_tags": [
    "endpoint",
    "process",
    "malware",
    "os:linux"
  ],
  "_version": "WzMzOTgsMV0=",
  "created_at": "2020-07-21T20:31:35.933Z",
  "created_by": "yo",
  "description": "This is a sample endpoint type exception",
  "id": "2c24b100-cb91-11ea-a872-adfddf68361e",
  "immutable": false,
  "list_id": "simple_list",
  "name": "Sample Endpoint Exception List",
  "namespace_type": "single",
  "tags": [
    "user added string for a tag",
    "malware"
  ],
  "tie_breaker_id": "c11c4d53-d0be-4904-870e-d33ec7ca387f",
  "type": "detection",
  "updated_at": "2020-07-21T20:31:35.952Z",
  "updated_by": "yo",
  "version": 1
}
```

```json
❯ ./update_list.sh
{
  "_version": "WzEsMV0=",
  "created_at": "2020-07-21T20:31:11.679Z",
  "created_by": "yo",
  "description": "Some other description here for you",
  "id": "ip_list",
  "immutable": false,
  "name": "Changed the name here to something else",
  "tie_breaker_id": "d6bd7552-84d1-4f95-88c4-cc504517b4e5",
  "type": "ip",
  "updated_at": "2020-07-21T20:31:47.089Z",
  "updated_by": "yo",
  "version": 2
}
```

```json
❯ ./update_exception_list.sh
{
  "_tags": [
    "endpoint",
    "process",
    "malware",
    "os:linux"
  ],
  "_version": "WzMzOTksMV0=",
  "created_at": "2020-07-21T20:31:35.933Z",
  "created_by": "yo",
  "description": "Different description",
  "id": "2c24b100-cb91-11ea-a872-adfddf68361e",
  "immutable": false,
  "list_id": "simple_list",
  "name": "Sample Endpoint Exception List",
  "namespace_type": "single",
  "tags": [
    "user added string for a tag",
    "malware"
  ],
  "tie_breaker_id": "c11c4d53-d0be-4904-870e-d33ec7ca387f",
  "type": "endpoint",
  "updated_at": "2020-07-21T20:31:56.628Z",
  "updated_by": "yo",
  "version": 2
}
```

### Checklist

- [x] [Unit or functional tests](https://github.com/elastic/kibana/blob/master/CONTRIBUTING.md#cross-browser-compatibility) were updated or added to match the most common scenarios