refac call submission and event watch

• refac call submission and event watch
• add commands
• implement config formatter
• document it

doc/config.md

+# Ğcli config 
+
+Some Ğcli commands require to have an address configured (for example to get account balance), some require to have a secret configured (to sign extrinsics).
+Ğcli allows to save what you want in a config file and to overwrite parts in command line arguments. Example:
+
+```sh
+# save Alice secret to config file
+cargo run -- -S predefined -s Alice config save
+
+# show config 
+cargo run -- config show
+# [stdout]
+# Ğcli config
+# duniter endpoint ws://localhost:9944
+# indexer endpoint http://localhost:8080/v1/graphql
+# address 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY (secret defined)
+
+# use different address in command line
+cargo run -- --address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n config show
+# [stdout]
+# Ğcli config
+# duniter endpoint ws://localhost:9944
+# indexer endpoint http://localhost:8080/v1/graphql
+# address 5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n (no secret)
+```
+
+You can see that if a secret is defined, the associated address is used, but if an other address is given, the secret is silenced.
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