refactor: rename common.rs to plugins.rs and update imports

src/digest_engine/program.rs

@@ -1,4 +1,4 @@
-use crate::common::ProgramWriter;
+use crate::plugins::ProgramWriter;
 use anyhow::{Context, Result, anyhow};
 use log::*;
 use std::env;

src/meta_plugin/program.rs

@@ -1,4 +1,4 @@
-use crate::common::ProgramWriter;
+use crate::plugins::ProgramWriter;
 use anyhow::{Context, Result, anyhow};
 use log::*;
 use std::env;

src/plugins.rs

@@ -0,0 +1,15 @@
+pub(crate) use std::io::Write;
+
+pub struct ProgramWriter {
+    stdin: std::process::ChildStdin,
+}
+
+impl Write for ProgramWriter {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        self.stdin.write(buf)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        self.stdin.flush()
+    }
+}