Show string hits on hover

- after the context is set
- hovering the identifiers in the condition can show string statistics

For example:
```
rule a {
  strings:
    $s00 = "test"
    $s01 = /another/
  condition:
    any of them
```

hovering over `$s00` identifier, could show match, match offset, match count, match virtual address, match lenght, etc.