[FR]: Keep explicit toolchain registration as the recommended default #80
Description
What is the current behavior?
#75 makes the recommended example registration of toolchains_protoc cleaner and simpler but makes it vulnerable to Bazel's surprising toolchain registration rules.
Describe the feature
bazel_dep looks a lot like it should be side-effect-free even though it's not. (Room for improvement in Bazel itself.) Our MODULE.bazel, for example, sorts our bazel_deps alphabetically for example near the top of the file. If users install toolchains_protoc in the new order-dependent way without explicit toolchain override, they're vulnerable to extremely surprising behavior where innocent reordering of bazel_dep calls can trigger a toolchain switch with commensurate build time regression. This is obviously just a matter of opinion but it's probably safer to recommend the more verbose boilerplate with explicit toolchain selection.