Linter rules get confused by merge markers

**Bicep version**
VS Code 0.4.1

**Describe the bug**
When dealing with a merge conflict, the linter rules can get a bit confused.

**To Reproduce**
In the below example, `resourceName` is clearly used

```bicep
var resourceName = 'test'

<<<<<<< HEAD
resource databaseAccount 'Microsoft.DocumentDB/databaseAccounts@2021-05-15' = {
=======
resource databaseAccount 'Microsoft.DocumentDB/databaseAccounts@2021-03-01-preview' = {
>>>>>>> origin/main
name: resourceName
//...
}
```

**Additional context**

It would be great if the linter is clever enough to be able to navigate the merge markers - in this case it should know not to warn as in all paths, the `resourceName` variable is used. That said, I imagine doing that could get complicated quickly so maybe it's sufficient to disable the linter until the merge markers are removed / resolved.

Start with the merge-conflict reproduction in the issue and trace how the Bicep linter processes source containing conflict markers. Compare the diagnostic for the unused resourceName variable before and after resolving the markers; done means the linter either handles all merge-marker paths correctly or is disabled while markers remain.

Written by the indexing model from the issue text.