Converting to monorepo

[ten3roberts]

It would be useful to convert the eyre, color-eyre, stable-eyre et.al. It would improve the discoverability of the different subcrates, as well as provide a single place where issues can be reported.

The current separate repositories makes it difficult for users to know where to report the errors as it may not initially be obvious if the source is in Eyre or an eyre hook implementer. It is a case of the classic "where should it go"

Merging them will improve the ease of issue creation and discovery, as well as overview.

The proposed structure will also improve ease of integration testing and examples and side-by-side development between the crates.

[ten3roberts]

Furthermore, it would provide a common CI between the crates, which ensures that each of the subcrates, such as color-eyre also gets tested and a single PR can test regressions on both the core eyre as well as our crates that use eyre at the same time.