feat(api): add proof-of-inclusion (PoI) endpoints (#854)

* Create proof-of-inclusion endpoints and initial logic

* Cleanup and test Merkle tree hasher

* Add db query for pastcone in whiteflag order

* Create PoI

* Improve hasher

* Improve hasher 2

* Implement contains check

* Impl proof validation part 1

* Clippy + Format

* Faulty License header complaint and clippy belitteling

* Fix validity check

* Add PoI api spec

* Add PoI link

* Impl proof validation part 2

* Cleanup Merkle hasher

* Cleanup Merkle proof

* Test dto roundtrip

* Format

* Remove key_manager module (as it was kinda bloat)

* Update api-poi.yaml

* Remove hex prefix for milestone validation

* Format

* I hate you clippy ... sometimes ;)

* Nit

* Don't need to fetch the milestone on validation

* Make PoI feature default

* Return error if decoding public key fails

* Include 'white_flag_index' into new combound index

* Refactor 'Hashable' enum

* Improve 'compute_proof' recursive fn

Co-authored-by: Alex Coats <alexandcoats@gmail.com>

* Refactor 'merkle_proof' module

* Document recursive fn

* Remove generics from the Merkle hasher

Co-authored-by: Alex Coats <alexandcoats@gmail.com>

* Nit

* Add PoI endpoints for applied blocks

* Remove dependency on lazy-static

* Remove binary response stubs

* Simplify audit path algo

* Further simplify and document audit path algo

* Improve docs

* Refer to Core REST API

* Debug 1

* Support single block cone audit paths

* Improve docs

* Impl AsRef for BlockId and make use of it

* Cleanup PoI routes

* More cleanup

Co-authored-by: Alex Coats <alexandcoats@gmail.com>
Co-authored-by: Jochen Görtler <grtlr@users.noreply.github.com>

Cargo.toml

@@ -61,7 +61,6 @@ ed25519 = { version = "1.5", default-features = false, features = [ "alloc", "pk
 ed25519-dalek = { version = "1.0", default-features = false, features = [ "u64_backend" ], optional = true }
 hex = { version = "0.4", default-features = false, optional = true }
 hyper = { version = "0.14", default-features = false, features = [ "server", "tcp", "stream" ], optional = true }
-lazy_static = { version = "1.4", default-features = false, optional = true }
 packable = { version = "0.7", default-features = false, optional = true }
 rand = { version = "0.8", default-features = false, features = [ "std" ], optional = true }
 regex = { version = "1.7", default-features = false, features = [ "std" ], optional = true }
@@ -78,6 +77,9 @@ tonic = { version = "0.8", default-features = false, optional = true }
 # Loki
 tracing-loki = { version = "0.2", default-features = false, features = [ "compat-0-2-1", "native-tls" ], optional = true }
 
+# PoI
+iota-crypto = { version = "0.15", default-features = false, features = [ "blake2b" ], optional = true }
+
 # Stardust types
 iota-types = { version = "1.0.0-rc", default-features = false, features = [ "api", "block", "std" ], optional = true }
 
@@ -92,6 +94,7 @@ default = [
     "inx",
     "loki",
     "metrics",
+    "poi",
     "stardust",
 ]
 analytics = [
@@ -105,7 +108,6 @@ api = [
     "dep:hex",
     "derive_more/from",
     "dep:hyper",
-    "dep:lazy_static",
     "dep:packable",
     "dep:rand",
     "dep:regex",
@@ -129,6 +131,10 @@ metrics = [
     "dep:influxdb",
     "dep:chrono",
 ]
+poi = [
+    "api",
+    "dep:iota-crypto",
+]
 rand = [
     "iota-types?/rand",
 ]