Add more integrations tests to People chains (#499)

https://github.com/open-web3-stack/polkadot-ecosystem-tests relies on
chopsticks to create E2E tests using periodically (roughly daily)
obtained runtimes from production relay chains/system parachains.

In particular,
open-web3-stack/polkadot-ecosystem-tests#63 does
this for the People chains.
In writing those tests, I was unable to use XCM to test
`pallet_identity::{kill_identity/add_username_authority/remove_username_authority}`.
I wrote this PR to replicate those tests at this layer, whose passing
status falsify the hypothesis that there may have been an issue with the
runtimes, and confirm that it was a problem with the way I wrote those
tests.

- [x] Does not require a CHANGELOG entry

integration-tests/emulated/chains/parachains/people/people-kusama/Cargo.toml

@@ -18,6 +18,9 @@ parachains-common = { workspace = true, default-features = true }
 cumulus-primitives-core = { workspace = true, default-features = true }
 emulated-integration-tests-common = { workspace = true }
 
+# Runtimes
+kusama-runtime-constants = { workspace = true, default-features = true }
+
 # Local
 people-kusama-runtime = { workspace = true }
 kusama-emulated-chain = { workspace = true }

integration-tests/emulated/chains/parachains/people/people-kusama/src/genesis.rs

@@ -18,14 +18,21 @@ use sp_core::storage::Storage;
 
 // Cumulus
 use cumulus_primitives_core::ParaId;
-use emulated_integration_tests_common::{build_genesis_storage, collators, SAFE_XCM_VERSION};
+use emulated_integration_tests_common::{
+	accounts, build_genesis_storage, collators, SAFE_XCM_VERSION,
+};
+use kusama_runtime_constants::currency::UNITS as KSM;
 use parachains_common::Balance;
 
+const ENDOWMENT: u128 = 1_000 * KSM;
 pub const PARA_ID: u32 = 1004;
 pub const ED: Balance = people_kusama_runtime::ExistentialDeposit::get();
 
 pub fn genesis() -> Storage {
 	let genesis_config = people_kusama_runtime::RuntimeGenesisConfig {
+		balances: people_kusama_runtime::BalancesConfig {
+			balances: accounts::init_balances().iter().cloned().map(|k| (k, ENDOWMENT)).collect(),
+		},
 		system: people_kusama_runtime::SystemConfig::default(),
 		parachain_info: people_kusama_runtime::ParachainInfoConfig {
 			parachain_id: ParaId::from(PARA_ID),

integration-tests/emulated/chains/parachains/people/people-polkadot/Cargo.toml

@@ -18,6 +18,9 @@ parachains-common = { workspace = true, default-features = true }
 cumulus-primitives-core = { workspace = true, default-features = true }
 emulated-integration-tests-common = { workspace = true }
 
+# Runtimes
+polkadot-runtime-constants = { workspace = true, default-features = true }
+
 # Local
 people-polkadot-runtime = { workspace = true }
 polkadot-emulated-chain = { workspace = true }

integration-tests/emulated/chains/parachains/people/people-polkadot/src/genesis.rs

@@ -18,14 +18,21 @@ use sp_core::storage::Storage;
 
 // Cumulus
 use cumulus_primitives_core::ParaId;
-use emulated_integration_tests_common::{build_genesis_storage, collators, SAFE_XCM_VERSION};
+use emulated_integration_tests_common::{
+	accounts, build_genesis_storage, collators, SAFE_XCM_VERSION,
+};
 use parachains_common::Balance;
+use polkadot_runtime_constants::currency::UNITS as DOT;
 
+const ENDOWMENT: u128 = 1_000 * DOT;
 pub const PARA_ID: u32 = 1004;
 pub const ED: Balance = people_polkadot_runtime::ExistentialDeposit::get();
 
 pub fn genesis() -> Storage {
 	let genesis_config = people_polkadot_runtime::RuntimeGenesisConfig {
+		balances: people_polkadot_runtime::BalancesConfig {
+			balances: accounts::init_balances().iter().cloned().map(|k| (k, ENDOWMENT)).collect(),
+		},
 		system: people_polkadot_runtime::SystemConfig::default(),
 		parachain_info: people_polkadot_runtime::ParachainInfoConfig {
 			parachain_id: ParaId::from(PARA_ID),