GH702 GH473: Added logger switch to MSBuild runner

[cpx86]

Relates to #702 and #473.

The gist of it is fairly simple. I've added an extension method for adding a logger switch to the MSBuildSettings class, similar to how property switches are added, like so:

public static MSBuildSettings WithLogger(this MSBuildSettings settings, string loggerAssembly, string loggerClass = null, string loggerParameters = null)

Calling that method should append an argument to MSBuild, like so:
/logger:loggerClass,loggerAssembly;loggerParameters

In addition to this, I added a MSBuildLogger class to hold the above assembly, class and parameters values, and to the MSBuildSettings class I added a collection property to hold instances of those.

[dnfclas]

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[dnfclas]

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[patriksvensson]

@cpx Looks good to me! 👍 Great job! I left some (minor) comments for you.

[cpx86]

@patriksvensson Done!

[devlead]

ICollection doesn't support indexing, LINQ could be one option istead
I.e.

var first = settings.Loggers.First();
var second = settings.Loggers.Skip(1).First();

and use those variables for the asserts.

[cpx86]

Oops, was a bit quick to push there :) Now it should work.

[devlead]

@cpx excellent, could you squash into 1 commit and rebase against latest develop, and ping it's when done.

[cpx86]

@devlead Done.

[cpx86]

Hmm, any idea why the OSX build failed? Is it due to changes in this PR or something else?

[patriksvensson]

@cpx Merged 👍 Thanks for this contribution! 😄