pw_bluetooth: Add 3 Event packets & format hci.emb

- ReadRemoteVersionInfoCompleteEvent
- ReadRemoteExtendedFeaturesCompleteEvent
- LEReadRemoteFeaturesCompleteSubevent

Also add enums
- CoreSpecificationVersion
- LEFeatureSet

Test: pw presubmit --step gn_emboss_build
Change-Id: I2ae96809ea0521626faa51fa10affeb9c061baec
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/157663
Reviewed-by: Faraaz Sareshwala <[email protected]>
Commit-Queue: Ali Saeed <[email protected]>