Add Ğtest genesis parsing in indexer

Currently the indexer is compatible with the Json Genesis format of ĞDev runtime.

• example in Duniter code: https://git.duniter.org/nodes/rust/duniter-v2s/-/blob/dabb2c0905cf0212470968261720d66da9eb3312/resources/gdev.json
• example in Indexer code: https://git.duniter.org/nodes/duniter-indexer/-/blob/9f80043790dc14bf4a1a71973ebbc4477999c995/resources/gdev_test.json

This format is more convenient than the one used in ĞTest runtime.

• example of ǦTest genesis file: https://git.duniter.org/nodes/rust/duniter-v2s/-/blob/dabb2c0905cf0212470968261720d66da9eb3312/node/specs/gtest_genesis.json

Some noticable differences are:

• the presence of the duniter-test-parameters pallet allowing to tweak the parameters in the genesis (useful for testing)
• the presence of genesis-parameters allowing to get useful properties for genesis accounts (like longer lifespan)
• the absence of fields like membership_expire_on allowing to distinguish from member and non-member identities

The indexer should be compatible with both formats:

• ĞDev used for development that can be adapted according to needs
• ĞTest used for production matching the current live ĞTest network