Provide more completion options for dotnet_naming_*

[BhaaLseN]

Installed product versions

• Visual Studio: 2017 Community
• This extension: 1.17.202

Description

At this point, it is fairly hard to create naming convention rules; mostly because there is little to no documentation (outside the .editorconfig files used by various dotnet repositories). Such rules (or perhaps in general, dotted identifiers like group.subgroup.name) could benefit from better completion, as well as more specific completion for the particular rules provided by dotnet_naming_style, dotnet_naming_symbols and dotnet_naming_rules. For example, while it is supported to insert the full dotnet_naming_rule.<naming_rule_title>.style line (and highlight <naming_rule_title> so we can type right away), there is no support for deleting .style and typing a dot to get intellisense offering style, severity and symbols as options. It could also be a neat addition to suggest currently existing naming rule titles from the current file when typing the dot after dotnet_naming_rule (to add other modifiers to them). Sticking with .style as example, it could provide a list of defined dotnet_naming_style members as suggestion to make it easier to match up but hard to mess up. At this point, typo'ing in one of the places makes the file invalid and has its rules ignored (or they don't do what was intended, depending on the typo). This should also provide suggestions for .symbols, using dotnet_naming_symbols as base.

Steps to recreate

1. Create a new .editorconfig file (or open an existing one). Insert rules for dotnet_naming_style.pascal_case_style.capitalization = pascal_case and dotnet_naming_style.camel_case_style.capitalization = camel_case if there aren't any yet.
2. Start typing dotnet_naming to get suggestions
3. Accept dotnet_naming_rule.<naming_rule_title>.style and give it a name (replacing <naming_rule_title> with some appropriate name)
4. Go to the end of the line (after the equal sign) and start typing pascal_case_style.
5. Duplicate the line, then delete from the end of the line until .style and hit the dot (or leave the dot in place, then use Ctrl+Space to invoke IntelliSense) in an attempt to create a new line for that same naming rule with .symbols

Current behavior

Step 3 inserts the snippet including the equal sign and highlights the string <naming_rule_title> Step 4 does not suggest styles from the file; it doesn't suggest anything Step 5 shows "no suggestions" (or, if you skip naming the rule in Step 3, it will show all 3 options)

Expected behavior

Step 3 stays as is Step 4 suggests camel_case_style and pascal_case_style from the file Step 5 shows severity, style and symbols as options inside IntelliSense.