Add analyzer and fixer for redundant DataField tag arguments

[Tayrtahn]

Adds an analyzer to provide an editor hint when a DataField attribute specifies a name that matches what the automatically generated name would be. Also adds a code fixer to automate the removal of these issues.

This is the first time I've messed with code analyzers/fixers, so please do review harshly if I did anything wrong, so I can get better at it.

That Fix All option looks pretty tempting...

[mirrorcult]

zased