Add special BuildMessageEventArgs types for task inputs, outputs, add item and remove item

[KirillOsenkov]

Currently more than half of all logging is by BuildMessageEventArgs with large message text.

They're categorized into four main categories:

1. Task Parameter:
2. Output Item(s):
3. Added Item(s):
4. Removed Item(s):

Messages typically reach up to 5MB in size for a single string.

Here's a sampling:
https://gist.github.com/KirillOsenkov/952b0798a760450cc2ae3b5aed3778c3

More stats and details here:
https://github.com/KirillOsenkov/MSBuildStructuredLog/wiki/BinLog-Stats

It would be better if we introduced a custom message type derived from BuildMessageEventArgs, and stored the items on the message in a structured way, without collapsing them into a single giant string. This way loggers would still get the same behavior, but loggers that are aware (such as BinaryLogger) would efficiently serialize the items without concatenating them into a single string unnecessarily.

I expect this to have huge benefits for logging throughput, memory pressure as well as binlog size and binlog loading speed.

[KirillOsenkov]

See here for the list of types currently deriving from BuildMessageEventArgs:
https://source.dot.net/#Microsoft.Build.Framework/BuildMessageEventArgs.cs,9c87bb1f74820496,references

[KirillOsenkov]

Another thing to pay attention to is we shouldn't be writing the Message field if we can avoid it:

[KirillOsenkov]

Start from ItemGroupLoggingHelper

[KirillOsenkov]

Fixed by #6155