Improve every text: titles, messages, and descriptions of the analyzers and code-fixes

[mikkelbu]

We should go through all texts: titles, messages, and descriptions of the analyzers and code-fixes and see if the text can be improved.

Extracted from #230

Nitpicking ahead, feel free to take it or leave it:

The message should be more casual and accessible. Right now, it is terse to the point of detracting from its readability. There are no articles (a/an/the) in the sentence. It is a good practice though to look for words to delete in every message without losing meaning or readability. For example, I think that the word 'provided' could be removed in the message above without loss of clarity. Here's a placeholder example: "The SameAs constraint always fails because the actual and expected values have mutually exclusive types."

A comprehensive resource that helps me is https://docs.microsoft.com/en-us/style-guide/top-10-tips-style-voice. I like what they're doing.