linera-views-derive: minor cleanups (#3854)

## Motivation

I wanted to [add a `view(skip)` directive to
`linera-views-derive`](#3845)
in order to facilitate the [removal of the `Extra` type from
`linera_views::Context`](#1948),
but it turns out to be more effort than it's worth to get skipped fields
into the struct when loading.

However, while I was there I made a couple of tweaks to
`linera-views-derive` that I think are improvements.

## Proposal

- add new constraints to `*View` implementations where they're required,
rather than relying on the consumer to add them: recursive constraints
on the field types, and `Self: Send + Sync` since we rely on
`async_trait`
- this should make the library more robust in the face of different
uses, and also provide slightly better errors when misused
- use `deluxe` for attribute parsing instead of doing it by hand: this
is less of a win than it was originally since without `view(skip)` we
only have one attribute to parse, but at least makes it easier to add
more in the future
- parse types for the `context` attribute rather than strings
- use the [`quote` repetition
syntax](https://docs.rs/quote/latest/quote/macro.quote.html#interpolation)
to save some code

<!--
Summarize the proposed changes and how they address the goal(s) stated
above.
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## Test Plan

CI.

## Release Plan

- Nothing to do / These changes follow the usual release cycle.

## Links
- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: Twey

Cargo.lock

@@ -77,6 +77,7 @@ criterion = { version = "0.5.1", default-features = false }
 crossbeam-channel = "0.5.14"
 custom_debug_derive = "0.6.1"
 dashmap = "5.5.3"
+deluxe = "0.5.0"
 derive_more = "1.0.0"
 dirs = "5.0.1"
 dyn-clone = "1.0.17"

Cargo.toml

@@ -8,7 +8,7 @@ use linera_sdk::{
 };
 
 #[derive(RootView, async_graphql::SimpleObject)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct AmmState {
     pub shares: MapView<Account, Amount>,
     pub total_shares_supply: RegisterView<Amount>,

examples/Cargo.lock

@@ -5,7 +5,7 @@ use linera_sdk::views::{linera_views, RegisterView, RootView, ViewStorageContext
 
 /// The application state.
 #[derive(RootView)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct CounterState {
     pub value: RegisterView<u64>,
 }

examples/amm/src/state.rs

@@ -5,7 +5,7 @@ use linera_sdk::views::{linera_views, RegisterView, RootView, ViewStorageContext
 
 /// The application state.
 #[derive(RootView)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct CounterState {
     pub value: RegisterView<u64>,
 }

examples/counter-no-graphql/src/state.rs

@@ -25,7 +25,7 @@ scalar!(Status);
 
 /// The crowd-funding campaign's state.
 #[derive(RootView, async_graphql::SimpleObject)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct CrowdFundingState {
     /// The status of the campaign.
     pub status: RegisterView<Status>,

examples/counter/src/state.rs

@@ -6,7 +6,7 @@ use linera_sdk::views::{linera_views, MapView, RegisterView, RootView, ViewStora
 
 /// The application state.
 #[derive(RootView, async_graphql::SimpleObject)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct EthereumTrackerState {
     pub ethereum_endpoint: RegisterView<String>,
     pub contract_address: RegisterView<String>,

examples/crowd-funding/src/state.rs

@@ -9,7 +9,7 @@ use linera_sdk::{
 
 /// The application state.
 #[derive(RootView)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct FungibleTokenState {
     pub accounts: MapView<AccountOwner, Amount>,
 }

examples/ethereum-tracker/src/state.rs

@@ -12,7 +12,7 @@ use linera_sdk::{
 
 /// The application state.
 #[derive(RootView, SimpleObject)]
-#[view(context = "ViewStorageContext")]
+#[view(context = ViewStorageContext)]
 pub struct GenNftState {
     // Map from token ID to the NFT data
     pub nfts: MapView<TokenId, Nft>,