Consolidate Resettable instances (#6604)

### Problem

Given that we always reset the entire `Store` and `CommandRunner` at once, the usage of `Resettable` in those modules is overly fine grained.

### Solution

Move the `Store` and `CommandRunner` into a single external `Resettable` instance, and then remove all internal usage of `Resettable`.

### Result

Simpler code, possibly slightly better performance.

src/rust/engine/fs/Cargo.toml

@@ -24,7 +24,6 @@ lmdb = "0.8"
 log = "0.4"
 parking_lot = "0.6"
 protobuf = { version = "2.0.4", features = ["with-bytes"] }
-resettable = { path = "../resettable" }
 sha2 = "0.7"
 serde = "1.0"
 serde_derive = "1.0"

src/rust/engine/fs/brfs/src/main.rs

@@ -679,7 +679,7 @@ fn main() {
     Some(address) => fs::Store::with_remote(
       &store_path,
       pool,
-      address.to_owned(),
+      address,
       args.value_of("remote-instance-name").map(str::to_owned),
       root_ca_certs,
       oauth_bearer_token,

src/rust/engine/fs/fs_util/src/main.rs

@@ -264,7 +264,7 @@ fn execute(top_match: &clap::ArgMatches) -> Result<(), ExitError> {
           Store::with_remote(
             &store_dir,
             pool.clone(),
-            cas_address.to_owned(),
+            cas_address,
             top_match
               .value_of("remote-instance_name")
               .map(str::to_owned),

src/rust/engine/fs/src/lib.rs

@@ -65,7 +65,6 @@ extern crate log;
 extern crate mock;
 extern crate parking_lot;
 extern crate protobuf;
-extern crate resettable;
 extern crate serde;
 extern crate sha2;
 #[cfg(test)]