Add rbpf-cli tool (#17378)

* Add rbpf-cli tool

* Replace explicit file type specification by required positional arg

- the type of file is determined automatically.  If ELF magic found,
  the program file is considered to be an executable ELF file, and
  an assembly input file otherwise.

* Add a note about tool's limitations and input format description

rbpf-cli/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "rbpf-cli"
+version = "1.8.0"
+description = "CLI to test and analyze eBPF programs"
+authors = ["Solana Maintainers <maintainers@solana.foundation>"]
+repository = "https://github.com/solana-labs/rbpf"
+homepage = "https://solana.com/"
+keywords = ["BPF", "eBPF", "interpreter", "JIT"]
+edition = "2018"
+
+[dependencies]
+clap = "3.0.0-beta.2"
+serde = "1.0.122"
+serde_json = "1.0.56"
+solana-bpf-loader-program = { path = "../programs/bpf_loader", version = "=1.8.0" }
+solana-logger = { path = "../logger", version = "=1.8.0" }
+solana-sdk = { path = "../sdk", version = "=1.8.0" }
+solana_rbpf = "=0.2.11"