Add optional generic type parms for variables on low level methods

[mvestergaard]

Similar to #3541, the ability to specify the type of variables is missing on watchQuery, query, mutate and subscribe methods in ApolloClient.

This PR adds optional generic type parameters to those methods that default to OperationVariables which seems to be used throughout the codebase.
Related to that, the parameters added in #3541 that were defaulted to any, now also use OperationVariables where it makes sense.

[apollo-cla]

	Warnings
⚠️	There are library changes, but not tests. That's OK as long as you're refactoring existing code

Generated by 🚫 dangerJS

[keyfu]

My errors.

ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-client/ApolloClient.d.ts (108,27): Generic type 'Query' requires 1 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-client/ApolloClient.d.ts (120,30): Generic type 'Fragment' requires 1 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-client/ApolloClient.d.ts (126,25): Generic type 'WriteQueryOptions<TData, TVariables>' requires 2 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-client/ApolloClient.d.ts (138,28): Generic type 'WriteFragmentOptions<TData, TVariables>' requires 2 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-client/ApolloClient.d.ts (149,24): Generic type 'WriteDataOptions' requires 1 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-cache-inmemory/lib/inMemoryCache.d.ts (25,35): Generic type 'Query' requires 1 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-cache-inmemory/lib/inMemoryCache.d.ts (26,41): Generic type 'Fragment' requires 1 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-cache-inmemory/lib/inMemoryCache.d.ts (27,25): Generic type 'WriteQueryOptions<TData, TVariables>' requires 2 type argument(s).
ERROR in /home/keyfu/dm-customerapp-ui/node_modules/apollo-cache-inmemory/lib/inMemoryCache.d.ts (28,28): Generic type 'WriteFragmentOptions<TData, TVariables>' requires 2 type argument(s).

I'm using angular 4 and this is my package.json
"apollo-angular": "1.0.1",
"apollo-angular-link-http": "1.0.2",
"apollo-cache-inmemory": "1.1.10",
"apollo-client": "2.2.8",
"graphql": "^0.13.2",
"graphql-tag": "^2.8.0",

[mvestergaard]

@keyfu I fail to see the relevance

[hwillson]

Looks great @mvestergaard - thanks very much!