Extract method should introduce variables with 'var' if that is the user preference.

Fixes #15219

Simplify API for tests to create options.

Use immutable arrays with SymbolInfo to avoid Enumerator allocations.

Add a feature to suggest using explicit tuple names when they are available.

Use an EquivalenceKey for 'InlineDeclaration' so we don't get multiple offerings of the same fix on a single line.

Remove unused Camel_Case resource

Remove hard coded info about System.ValueTuple now that we're adding it to the nuget index.

Use an EquivalenceKey for 'InlineDeclaration' so we don't get multiple offerings of the same fix on a single line.

Merge dev15-rc2 into master

* Add instructions for getting an Insider VSIX

This is required to get a good IDE experience now that we're using C# 7 in the compiler.

* Update directions

* Specify the RC VSIX as the one to install

Do not offer UseObjectInitializer if it would change implicit-member-access semantics.

Fixes #15012

Move 'Add Braces' to the new FixAll' system.

Move 'UseImplicitType' onto the new FixAll system.

Pull common FixAll logic into some helper base types that we can use across many of our code style fixes.