Add syntax highlighting for records and init accessors

[cschierig]

This pull request adds syntax highlighting for records and init accessors.
It currently doesn't include positional record declarations as I haven't figured them out yet regex-wise.

This partly addresses #202 (Records highlighting is not supported).

[dnfadmin]

All CLA requirements met.

[kasperk81]

looks like you didn't build the project (with npm i which also runs gulp), otherwise you will have four files change in this pr.

[JoeRobich]

@CozyPenguin Thanks for the contribution. I am going to add some tests and we will get this merged.

[kasperk81]

@JoeRobich, please also check-in the updated package-lock.json so there is no diff in clean repo after the build:

git clone https://github.com/dotnet/csharp-tmLanguage
cd csharp-tmLanguage
npm install # which also run gulp and builds it
git status

with current master on ubuntu with npm v7.5.2 and node v12.21.0, it gives:

	modified:   package-lock.json
	modified:   package.json

[JoeRobich]

@kasperk81 Can you check again?

[kasperk81]

👍 retest the latest with npm v7.17 and above (latest is 7.19) no diffs after the build of fresh clone.