Update protobuf.js to v8.6.0

[dcodeIO]

• Upgrades protobuf.js to ^8.6.0 and protobufjs-cli to ^2.5.1
• Switches to default ESM output, removing the old custom wrapper workaround
• Uses the ProtoJSON and Text Format extension entrypoints
• No longer excludes the proto2 conformance input
• Removes the old UnknownOrdering special case for unknown fields
• Documents that Text Format conformance is tracked separately
• Removes the obsolete protobuf.js implementation caveats that no longer apply

Refs bufbuild/protobuf-es#1424

[CLAassistant]

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