feat!: break mono-package into individual packages

[hspitzley-czi]

Updates this repo structure so each package has its own go.mod. This allows projects relying on these packages to only bring in the sub-dependencies needed by the package they rely on instead of every sub-dependency from every package in this repo.

Process:

• copy go.mod and go.sum into each package directory
• run go mod tidy in each package dir
• removed unnecessary replace/exclude directives in each package-specific go.mod
• updated GH Actions to account for new structure