src: rename CONNECTION provider to SSLCONNECTION
Currently the async provider type CONNECTION is used in node_crypto.h and it might be clearer if it was named SSLCONNECTION as suggested by addaleax.
This commit renames only the provider type as I was not sure if it was alright to change the class Connection as well.
Refs: https://github.com/nodejs/node/pull/12967#discussion_r115978735
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
src