feat: --config parameter to specify picodata configuration file

Summary

• Remove --init-cfg option: now it will say to use --config instead

• fix: move tiers configuration to config.yaml

Change configuration file format:

• before:

tier:
  storage:
    replication_factor: 2

• after:

cluster:
  tiers:
    storage:
      replication-factor: 2

• feat: try reading ./config.yaml by default

• feat: validate configuration against storage (currently only instance_id)

• feat: --config parameter to specify picodata configuration file

Also here we refactor all the places where we checked command line parameters, because now PicodataConfig is the main source of this information.

---

• Close #...
• Target branch: master
• Changes should be cherry-picked to 24.1: yes / no
• Docs follow-up: not necessary / new issue

pico_proc_macro/src/lib.rs

+use quote::quote;
+
+#[proc_macro_derive(Introspection)]
+pub fn derive_introspection(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = syn::parse_macro_input!(input as syn::DeriveInput);
+    let name = &input.ident;
+
+    let mut field_names = vec![];
+    match &input.data {
+        syn::Data::Struct(ds) => match &ds.fields {
+            syn::Fields::Named(fs) => {
+                for field in &fs.named {
+                    let field_name = field.ident.as_ref().unwrap();
+                    field_names.push(field_name.to_string());
+                }
+            }
+            _ => {}
+        },
+        _ => {}
+    }
+
+    quote! {
+        impl #name {
+            pub const FIELD_NAMES: &'static [&'static str] = &[
+                #( #field_names, )*
+            ];
+        }
+    }
+    .into()
+}