py/tools: Namespace repo packages to prevent conflict

[phlax]

This allows repo tooling to work externally alongside our namepsaced pypi packages

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[repokitteh-read-only]

CC @envoyproxy/dependency-shepherds: Your approval is needed for changes made to (bazel/.*repos.*\.bzl)|(bazel/dependency_imports\.bzl)|(api/bazel/.*\.bzl)|(.*/requirements\.txt)|(.*\.patch).
envoyproxy/dependency-shepherds assignee is @htuch

🐱

Caused by: #29787 was opened by phlax.

see: more, trace.

[phlax]

this requires an upstream fix bazel-contrib/bazel-lib#547

it also has a really dirty hack (repeated) - its v similar to the ones we used to have to patch sys.path - in fact that hack may work and be cleaner - this was was v much a distressed hack

breaking out bits of here as they are resolved (eg #29786) - downstream target is envoyproxy/envoy-website#336

[phlax]

@htuch this is what is left to make the external docs/protodoc build work

essentially the problem boils down to the fact that we have pip deps that are namespaced envoy.* and rules_python is creating non namespaced-packages for tool/* which externally it sees as envoy/tools/*

not sure how best to resolve - not as current in this Pr - at least without some cleanup - will try and follow up one way or anotherr - for now the website is carrying the patch from this pr

[phlax]

this should work now and is a i think a much more elegant/reliable/bazelish solution

essentially it injects namespaced init.py into all the places that were making it impossible to use tooling externally

i may have missed a couple but this will at least allow external building of docs, and use of most of the linting tools