[SM-1178] Rename Service Accounts to Machine Accounts (#698)

## Type of change

<!-- (mark with an `X`) -->

- [ ] Bug fix
- [x] New feature development
- [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

## Objective

<!--Describe what the purpose of this PR is. For example: what bug
you're fixing or what new feature you're adding-->

Rename instances (& similar) of "service account" to "machine account".
This only impacts public facing text, so items in README's,
documentation, help docs, etc.

## Before you submit

- Please add **unit tests** where it makes sense to do so

crates/bitwarden-napi/README.md

@@ -20,7 +20,7 @@ const accessToken = "-- REDACTED --";
 
 const client = new BitwardenClient(settings, LogLevel.Info);
 
-// Authenticating using a service accounts access token
+// Authenticating using a machine account access token
 const result = await client.loginWithAccessToken(accessToken);
 if (!result.success) {
   throw Error("Authentication failed");

crates/bws/src/main.rs

@@ -40,7 +40,7 @@ struct Cli {
     #[arg(short = 'c', long, global = true, value_enum, default_value_t = Color::Auto, help="Use colors in the output")]
     color: Color,
 
-    #[arg(short = 't', long, global = true, env = ACCESS_TOKEN_KEY_VAR_NAME, hide_env_values = true, help="Specify access token for the service account")]
+    #[arg(short = 't', long, global = true, env = ACCESS_TOKEN_KEY_VAR_NAME, hide_env_values = true, help="Specify access token for the machine account")]
     access_token: Option<String>,
 
     #[arg(