Freshness Pass Cpp Editing Page

[AlexandraKemperMS]

Updating the editing page to include more features that we support, reformatting, and doing an overall freshness pass. Also adding a lot of features of the extension which are split with a new refactoring page.

Features add:

• Go to Declaration
• Go to References
• Go to Type Definition
• Call Hierarchy
• Extract Method
• Code Action: Add missing includes
• Create Declaration/Definition

[AlexandraKemperMS]

@microsoft/vscode-c-language-server could you please review this documentation PR, especially if you own one of the features added.