Update Feature Flags (#6981)

* Update Feature Flags

Added new feature flags which could be supported without issues.
Removed all deprecated feature flags and only match supported flags.
Do not error on invalid flags during load, but do on config save via admin interface.
During load it will print a `WARNING`, this is to prevent breaking setups when flags are removed, but are still configured.

There are no feature flags anymore currently needed to be set by default, so those are removed now.

Signed-off-by: BlackDex <black.dex@gmail.com>

* Adjust code a bit and add Diagnostics check

Signed-off-by: BlackDex <black.dex@gmail.com>

* Update .env template

Signed-off-by: BlackDex <black.dex@gmail.com>

---------

Signed-off-by: BlackDex <black.dex@gmail.com>

src/api/admin.rs

@@ -32,7 +32,7 @@ use crate::{
     mail,
     util::{
         container_base_image, format_naive_datetime_local, get_active_web_release, get_display_size,
-        is_running_in_container, NumberOrString,
+        is_running_in_container, parse_experimental_client_feature_flags, FeatureFlagFilter, NumberOrString,
     },
     CONFIG, VERSION,
 };
@@ -734,6 +734,13 @@ async fn diagnostics(_token: AdminToken, ip_header: IpHeader, conn: DbConn) -> A
 
     let ip_header_name = &ip_header.0.unwrap_or_default();
 
+    let invalid_feature_flags: Vec<String> = parse_experimental_client_feature_flags(
+        &CONFIG.experimental_client_feature_flags(),
+        FeatureFlagFilter::InvalidOnly,
+    )
+    .into_keys()
+    .collect();
+
     let diagnostics_json = json!({
         "dns_resolved": dns_resolved,
         "current_release": VERSION,
@@ -756,6 +763,7 @@ async fn diagnostics(_token: AdminToken, ip_header: IpHeader, conn: DbConn) -> A
         "db_version": get_sql_server_version(&conn).await,
         "admin_url": format!("{}/diagnostics", admin_url()),
         "overrides": &CONFIG.get_overrides().join(", "),
+        "invalid_feature_flags": invalid_feature_flags,
         "host_arch": env::consts::ARCH,
         "host_os":  env::consts::OS,
         "tz_env": env::var("TZ").unwrap_or_default(),