fi-0167: Cannot constrain twice {:#fi-0167}

Re-assigning the transport bound for a client_end or server_end that has already had a transport bound defined through an alias declaration is prohibited:

{% include “docs/reference/fidl/language/error-catalog/label/_bad.md” %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/bad/fi-0167.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}

Instead, aliasing of client_end and server_end types should be avoided entirely:

{% include “docs/reference/fidl/language/error-catalog/label/_good.md” %}

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/good/fi-0167.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}

This is disallowed to avoid confusion and compiler implementation complexity.