Implement simple allocator using enif_{alloc,free} #1098

Job	Run time
Format	20s
Build ubuntu stable	24s
Build ubuntu nightly	24s
Build windows stable	54s
Build windows nightly	51s
Build macos stable	1m 23s
Build macos nightly	1m 17s
Clippy ubuntu	18s
Clippy windows	1m 12s
Clippy macos	48s
OTP 26 / Elixir 1.16 / Rust stable / OS macos	1s
OTP 26 / Elixir 1.16 / Rust stable / OS windows	10s
OTP 26 / Elixir 1.16 / Rust stable / OS ubuntu	1s
OTP 26 / Elixir 1.16 / Rust nightly / OS macos	1s
OTP 26 / Elixir 1.16 / Rust nightly / OS windows	44s
OTP 26 / Elixir 1.16 / Rust nightly / OS ubuntu	1m 21s
OTP 26 / Elixir 1.15 / Rust stable / OS macos	1s
OTP 26 / Elixir 1.15 / Rust stable / OS windows	1m 9s
OTP 26 / Elixir 1.15 / Rust stable / OS ubuntu	1m 10s
OTP 26 / Elixir 1.15 / Rust nightly / OS macos	1s
OTP 26 / Elixir 1.15 / Rust nightly / OS windows	1m 7s
OTP 26 / Elixir 1.15 / Rust nightly / OS ubuntu	1m 12s
OTP 25 / Elixir 1.15 / Rust stable / OS macos	1s
OTP 25 / Elixir 1.15 / Rust stable / OS windows	1m 9s
OTP 25 / Elixir 1.15 / Rust stable / OS ubuntu	1m 8s
OTP 25 / Elixir 1.15 / Rust nightly / OS macos	29s
OTP 25 / Elixir 1.15 / Rust nightly / OS windows	1m 9s
OTP 25 / Elixir 1.15 / Rust nightly / OS ubuntu	1m 15s
OTP 24 / Elixir 1.14 / Rust stable / OS macos	28s
OTP 24 / Elixir 1.14 / Rust stable / OS windows	1m 9s
OTP 24 / Elixir 1.14 / Rust stable / OS ubuntu	1m 5s
OTP 24 / Elixir 1.14 / Rust nightly / OS macos	51s
OTP 24 / Elixir 1.14 / Rust nightly / OS windows	1m 10s
OTP 24 / Elixir 1.14 / Rust nightly / OS ubuntu	1m 11s
	25m 54s

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