[query-engine] Engine implementation folders (open-telemetry#563)

## Changes

* Define folders/crates to contain engine implementations

Author: CodeBlanch

rust/experimental/query_engine/Cargo.toml

@@ -1,7 +1,9 @@
 [workspace]
 members = [
     "expressions",
-    "kql-parser"
+    "kql-parser",
+    "engine-columnar",
+    "engine-recordset",
 ]
 resolver = "2"
 

rust/experimental/query_engine/README.md

@@ -1,3 +1,13 @@
 # Query Engine
 
-TODO
+This folder contains work in progress to implement an engine which can run
+queries over different data shapes.
+
+## Folder structure
+
+|Name            |Description                                                                              |
+|----------------|-----------------------------------------------------------------------------------------|
+|expressions     |Intermediary language and syntax tree for the query engine                               |
+|kql-parser      |Parser to turn KQL queries into query engine expressions (syntax trees)                  |
+|engine-columnar |Query engine implementation which takes a syntax tree and runs over columnar data (arrow)|
+|engine-recordset|Query engine implementation which takes a syntax tree and runs over set or records (otlp)|

rust/experimental/query_engine/deny.toml

@@ -66,7 +66,8 @@ allow = [
     "Apache-2.0",
     # TODO: Confirm legal use of Unicode-3.0
     # See https://github.com/open-telemetry/otel-arrow/issues/313
-    "Unicode-3.0"
+    "Unicode-3.0",
+    "CC0-1.0"
 ]
 # The confidence threshold for detecting a license from license text.
 # The higher the value, the more closely the license text must be to the

rust/experimental/query_engine/engine-columnar/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "data_engine_columnar"
+version.workspace = true
+authors.workspace = true
+repository.workspace = true
+license.workspace = true
+publish.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+arrow = "55"
+
+thiserror = { workspace = true }

rust/experimental/query_engine/engine-columnar/src/lib.rs

@@ -0,0 +1 @@
+

rust/experimental/query_engine/engine-recordset/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "data_engine_recordset"
+version.workspace = true
+authors.workspace = true
+repository.workspace = true
+license.workspace = true
+publish.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+
+thiserror = { workspace = true }

rust/experimental/query_engine/engine-recordset/src/lib.rs

@@ -0,0 +1 @@
+