Windows CRLF Issue

[timbess]

The way the config.toml is currently included in the digest is as a literal string rather than the parsed AST form. This causes instability in the digest on windows because it will have CRLF line endings instead of LF on linux/mac. This happens because the starlark code around cargo-bazel injects the string literal of the file into a JSON structure that is later parsed correctly as a string of the entire config.toml. It'd probably be better to parse it as TOML in the starlark as a separate step before it's fed into cargo-bazel, but for now this should fix the bug without doing a bigger overhaul.

#3455