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.

Start by tracing how context is set and how hover information is produced for identifiers in the YARA language server. Use the `$s00` example to determine which string statistics are available, and consider the work done when hovering a string identifier displays the agreed match details.

Written by the indexing model from the issue text.