Part of #236938
## Summary
This PR adds `AST` support for the new`FUSE` parameters.

```
fuseCommand
    : DEV_FUSE (fuseType=identifier)? (fuseConfiguration)*
    ;

fuseConfiguration
    : SCORE BY score=qualifiedName
    | KEY BY key=fields
    | GROUP BY group=qualifiedName
    | WITH options=mapExpression
    ;
```

`FUSE <fuse_method> SCORE BY <score_column> GROUP BY <group_column> KEY
BY <key_columns> WITH <options>`

### Some Examples
`| FUSE LINEAR # Merge results using linear combination of scores (equal
weights by default)`

`| FUSE LINEAR WITH { "normalizer": "minmax" } # Linear combination with
min-max normalization (scales scores to 0-1 range)
 `

`| FUSE LINEAR WITH { "weights": { "fork1": 0.7, "fork2": 0.3 },
"normalizer": "minmax" } # Weighted linear combination: 70% lexical, 30%
semantic, with min-max normalization`

### Note
No tests has been added to check parameters or fields with dots, as the
parser needs this
[fix](elastic/elasticsearch#135901) to be merged
to support them.


### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

Part of elastic#236938
## Summary
This PR adds `AST` support for the new`FUSE` parameters.

```
fuseCommand
    : DEV_FUSE (fuseType=identifier)? (fuseConfiguration)*
    ;

fuseConfiguration
    : SCORE BY score=qualifiedName
    | KEY BY key=fields
    | GROUP BY group=qualifiedName
    | WITH options=mapExpression
    ;
```

`FUSE <fuse_method> SCORE BY <score_column> GROUP BY <group_column> KEY
BY <key_columns> WITH <options>`

### Some Examples
`| FUSE LINEAR # Merge results using linear combination of scores (equal
weights by default)`

`| FUSE LINEAR WITH { "normalizer": "minmax" } # Linear combination with
min-max normalization (scales scores to 0-1 range)
 `

`| FUSE LINEAR WITH { "weights": { "fork1": 0.7, "fork2": 0.3 },
"normalizer": "minmax" } # Weighted linear combination: 70% lexical, 30%
semantic, with min-max normalization`

### Note
No tests has been added to check parameters or fields with dots, as the
parser needs this
[fix](elastic/elasticsearch#135901) to be merged
to support them.


### Checklist

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios