mixed line endings in source files

[Eskibear]

Currently by running git ls-files --eol, you'll see most of files are LF-based.

Among them there are a few are CRLF-based and one with mixed EOLs.

$ git ls-files --eol | grep crlf
i/crlf  w/crlf  attr/                   .travis.yml
i/crlf  w/crlf  attr/                   src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs
i/crlf  w/crlf  attr/                   src/Microsoft.Extensions.Configuration.AzureAppConfiguration/CryptoService.cs

$ git ls-files --eol | grep mixed
i/mixed w/mixed attr/                   src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationExtensions.cs

(use findstr instead of grep on windows)

This can lead to some inconvenience and sometimes you can see below warning dialog in VS.

Thus, I suggest that we make EOL consistent, i.e. renormalize EOL of above four files to LF.