gtest genesis parsing

• only embed chainspec when feature enabled
• change existential deposit to match g1v1
• adapt genesis parsing to real-world data

# build with gtest feature
cargo build --release --features gtest --no-default-features
# run with custom genesis
DUNITER_GTEST_GENESIS=~/dev/py-g1-migrator/output/gtest_genesis.json duniter --tmp --alice --chain=gtest_dev

node/src/chain_spec/gdev.rs

@@ -688,7 +688,7 @@ fn genesis_data_to_gdev_genesis_conf(
     let super::gen_genesis_data::GenesisData {
         accounts,
         certs_by_receiver,
-        first_ud_value,
+        first_ud,
         first_ud_reeval,
         identities,
         initial_authorities,
@@ -764,7 +764,7 @@ fn genesis_data_to_gdev_genesis_conf(
         },
         universal_dividend: UniversalDividendConfig {
             first_reeval: first_ud_reeval,
-            first_ud_value,
+            first_ud,
             initial_monetary_mass,
             ud,
         },