Fix FinalLocalVariable Recipe for Multiple Variable Declarations

[Anmol202005]

Follow up of: #40

The FinalLocalVariableCheck recipe has partial coverage and doesn't handle cases where multiple variables are declared together.

Example:

int a, b, c;  // Only one variable has violation

Currently, cases like this where only one variable in a multi-variable declaration needs to be made final, the recipe won't process it.
Update the recipe to properly handle multiple variable declarations and apply the final modifier correctly.

[Anmol202005]

@rdiachenko .

int a, b, c;  // Only a variable has violation

if in the above declaration only variable a should be declared final.
we can`t fix it.

[rdiachenko]

Can you run Checkstyle on few examples. What violations does it produce?

if in the above declaration only variable a should be declared final.

The goal is to fix whatever Checkstyle complaints about. If only one variable should be declared final, we can try to refactor this code by the recipe:

1. Take variable declaration
2. Take its siblings, so we want a full list of variables participating in the same declaration
3. Split this list into two: final variable and non-final
4. Apply the change, so that int a, b, c; becomes as follows, for instance:

final int b;
int a, c;

[Anmol202005]

@rdiachenko raised draft PR but requires #95 for end to end implementation.

[rdiachenko]

@Anmol202005 before we take the marker approach, could you check this documentation - https://docs.openrewrite.org/authoring-recipes/multiple-visitors

I think we can try similar approach with two visitors. The first visitor will find all variable declarations that Checkstyle complains about, the second visitor will fix them. We don't need markers here, because in the first visitor we don't change the tree, so violation locations shouldn't move.

I'd like to postpone marker approach until we really need it as it is complex to do it right, and better to take simpler solution if we can.