Expand the sample to cover all language features

[octref]

https://microsoft.github.io/language-server-protocol/specification

Testing using vscode commands:

• completion
• hover
• signatureHelp
• definition
• typeDefinition
• implementation
• references
• documentHighlight
• documentSymbol
• codeAction
• codeLens
• codeLens resolve
• documentLink
• documentColor
• colorPresentation
• formatting
• rangeFormatting
• onTypeFormatting
• rename

Special

• Diagnostics

Not doable now:

• completion resolve
• documentLink resolve