Sign collector and update visibility

[MarcoRossignoli]

contributes to #555

I've signed collector and updated all visibility of object.
This is a first step to expose coverage.core.dll as a lib, we'll expose only public pertinent object through interfaces/factories to be free to update internal implementation.

AFTER MERGE WE MUST UPDATE VSTEST RUNTIME AND DO SOME TESTS https://github.com/microsoft/vstest/pull/2020/files

cc: @tonerdo @vagisha-nidhi @petli

[MarcoRossignoli]

coverlet.collector.snk public key

C:\git\coverlet\src\coverlet.collector (signcollector -> origin)
λ sn -tp token.snk

Microsoft (R) .NET Framework Strong Name Utility  Version 4.0.30319.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key (hash algorithm: sha1):
00240000048000009400000006020000002400005253413100040000010001003d23b9ef372215
da7c81af920b919db5799fd021a1ca10b2e9e0ddac71237a29f8f6361a805a747457e561a7d616
417f1870cda099486df25d580a4e11a0738293342881566254d7840e42f42fb9bfd8e8dca354df
7dc68db14b2d0cd79bb2bf7afdbd62bd948d81b534cba7a326cf6ee840a1aee5dba0a1c660b308
13ca99e5

Public key token is 4beb1ad7f05a1c71

C:\git\coverlet\src\coverlet.collector (signcollector -> origin)
λ sn -t token.snk

Microsoft (R) .NET Framework Strong Name Utility  Version 4.0.30319.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key token is 4beb1ad7f05a1c71

[tonerdo]

I have reservations about exposing coverlet.core publicly

[MarcoRossignoli]

I have reservations about exposing coverlet.core publicly

@tonerdo I don't have a strong opinion about it...I don't know if this scenario makes sense.
If you remember we talked about it some time ago #212 and also in there I wasn't so "happy" about.
We can decide to wait for more community pressure.
BTW do you agree in hiding all implementation to be more clean?
I like the idea that if someone add reference directly to coverlet libs doesn't see anything.
@petli thought?

The idea of this PR is sign and "clean", I labeled with no merge because we need to have some feedback by vstest team, I've asked here https://github.com/microsoft/vstest/pull/2020/files#r327122741
cc: @vagisha-nidhi @cltshivash

[MarcoRossignoli]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[MarcoRossignoli]

@vagisha-nidhi merged FYI