use contains_key instead of .get().is_{some, none}()

Fixes the clippy lints:

warning: unnecessary use of `get("lo").is_none()`
   --> proxmox-network-api/src/config/parser.rs:603:30
    |
603 |         if config.interfaces.get("lo").is_none() {
    |            ------------------^^^^^^^^^^^^^^^^^^^
    |            |
    |            help: replace it with: `!config.interfaces.contains_key("lo")`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_get_then_check
    = note: `#[warn(clippy::unnecessary_get_then_check)]` on by default

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>

proxmox-access-control/src/acl.rs

@@ -973,14 +973,14 @@ mod test {
             let node = tree.find_node(path);
             assert!(node.is_some());
             if let Some(node) = node {
-                assert!(node.users.get(&user1).is_none());
+                assert!(!node.users.contains_key(&user1));
             }
         }
         for path in &user2_paths {
             let node = tree.find_node(path);
             assert!(node.is_some());
             if let Some(node) = node {
-                assert!(node.users.get(&user2).is_some());
+                assert!(node.users.contains_key(&user2));
             }
         }
 
@@ -990,7 +990,7 @@ mod test {
             let node = tree.find_node(path);
             assert!(node.is_some());
             if let Some(node) = node {
-                assert!(node.users.get(&user2).is_none());
+                assert!(!node.users.contains_key(&user2));
             }
         }
 

proxmox-acme-api/src/plugin_config.rs

@@ -67,7 +67,7 @@ pub(crate) fn plugin_config() -> Result<(PluginData, ConfigDigest), Error> {
     let digest = ConfigDigest::from_slice(content.as_bytes());
     let mut data = CONFIG.parse(plugin_cfg_filename, &content)?;
 
-    if data.sections.get("standalone").is_none() {
+    if !data.sections.contains_key("standalone") {
         let standalone = StandalonePlugin::default();
         data.set_data("standalone", "standalone", &standalone)
             .unwrap();

proxmox-network-api/src/config/parser.rs

@@ -600,7 +600,7 @@ impl<R: BufRead> NetworkParser<R> {
             }
         }
 
-        if config.interfaces.get("lo").is_none() {
+        if !config.interfaces.contains_key("lo") {
             let mut interface = Interface::new(String::from("lo"));
             set_method_v4(&mut interface, NetworkConfigMethod::Loopback)?;
             interface.interface_type = NetworkInterfaceType::Loopback;

proxmox-section-config/src/lib.rs

@@ -322,7 +322,7 @@ impl SectionConfig {
         let mut done = HashSet::new();
 
         for section_id in &config.order {
-            if config.sections.get(section_id).is_none() {
+            if !config.sections.contains_key(section_id) {
                 continue;
             };
             list.push(section_id);