Remove app crate and related components (#170)

* Remove spicepod

* Fix PR branch build/lint after spicepod removal

* Remove app crate and related components

- Deleted the `app` crate from the workspace, including its `Cargo.toml` and source files.
- Updated the root `Cargo.toml` to remove references to the `app` crate.
- Removed the `get_runtime_param` and `user_agent_collection` methods from the `App` struct.
- Cleaned up the `test-framework` crate by removing unnecessary dependencies and code related to the `app` crate.
- Adjusted the `DataConsistencyArgs` struct to remove the `compare_spicepod` field.

* docs: note removal of legacy app/spicepod crates

* Update README.md

Co-authored-by: Phillip LeBlanc <phillip@leblanc.tech>

---------

Co-authored-by: Phillip LeBlanc <phillip@leblanc.tech>

Author: lukekim

Cargo.lock

@@ -3,7 +3,7 @@ exclude = ["system-adapters/databricks"]
 members = [
     ".",
     "crates/adbc_client",
-    "crates/app", "crates/checkpointer",
+    "crates/checkpointer",
     "crates/data-generation",
     "crates/duration-parse", "crates/etl",
     "crates/flight_client",
@@ -83,7 +83,6 @@ schemars = "1.2.0"
 secrecy = "0.10.3"
 serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1"
-spicepod = { git = "https://github.com/spiceai/spice.git", rev = "46155f7fdc27aa1393b0451347f78b6aad66839a" }
 sha2 = "0.10.8"
 snafu = "0.8.6"
 sysinfo = "0.37.2"