Fixed handling arrays with keys having brackets in array matcher

[cezarystepkowski]

Array matcher is throwing an exception when array has a key with brackets.

See example below:

Value:

{
  "foo[key]": "value"
}

Pattern:

{
  "foo[key]": "@string@"
}

The reason for that is because Symfony\Component\PropertyAccess\Exception\InvalidPropertyPathException is thrown in Symfony\Component\PropertyAccess\PropertyPath constructor because such key does not match regex for valid property.

This PR attempts to fix it.

I looked into the usage of PropertyPath and PropertyAccessor in ArrayMatcher and it seems that it was needed only to perform simple operation (basically stripping [ and ] from beginning and end of a path string). I simplified the operation by adding a method getKeyFromAccessPath instead of relying on PropertyAccessor.

All tests passed so I assume that it will not break anything else :)

Additionally, it turned out that symfony/property-access is not used anywhere else in the project so I removed it from Composer dependencies.

[norberttech]

@cezarystepkowski sorry for a long time it took me to review your work. I merged this PR into #204, which also remove few other hard dependencies making phpmatcher free nice and small.
Thank you for your contribution 🙌