[semantic highlighting] deprecate 'member' add 'method'

[aeschli]

From microsoft/language-server-protocol#1087

'member' has confused several users. Deprecating 'member', adding 'method' instead.

For now 'member' will continue to color like a method.

[aeschli]

fixed by 07d680b

[aeschli]

To verify open the https://github.com/microsoft/vscode-extension-samples/tree/master/semantic-tokens-sample
and test that method works as well as member (deprecated, but still working)