implement quotas and refund transaction fees

This MR implements a way to link an account to an identity in order to use identity's quotas of free transactions to refund fees in on_idle.

See https://forum.duniter.org/t/implementation-des-quotas/11543 for whole discussion.

TODO

• automatically link the account of a newly created identity
• choose whether quotas should be decoupled from identity pallet
• find better names for coupling types and traits
• replace hardcoded RELOAD_RATE and MAX_QUOTAS by parameters
• test quotas reloading behavior (easier with parametric reload rate and max quotas)
• test hooks when identity status change
• propagate changes brought to gdev to other runtimes
• get new_owner_key and link_identity tests working (see forum)
• rebase on !182 (merged) to have well defined treasury initial value
• add error message when the identity is not eligible to be refunded (add 'Disabled' state ?)
• discuss return type of quotas functions (result or infallible)
• discuss if IdtyData should really be a runtime type

Benchmark and opti

• rebase on !185 (merged) to get benchmarks from other pallets fixed
• use benchmark weight in estimation of batch refund
• benchmark calls (will go in separate MR)
• (optimization) avoid calling treasury account_id

Documentation (to do on duniter website)

• document user calls to link / unlink identity to an account
• document global quotas behavior in a friendly manner (user doc goes to duniter.org website)

changed milestone to %runtime-700

added RN-runtime label

assigned to @HugoTrentesaux

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• 04ed9692 - move quotas to separate pallet

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marked the checklist item discuss whether quotas should be decoupled from identity pallet as completed

marked the checklist item find better names for coupling types and traits as completed

marked the checklist item discuss if IdtyData should really be a runtime type as completed

marked the checklist item replace hardcoded RELOAD_RATE and MAX_QUOTAS by parameters as completed

marked the checklist item test quotas reloading behavior (easier with parametric reload rate and max quotas) as completed

changed the description

After moving quotas to a separate pallet, it becomes obvious that it was the good approach:

• modularity
• better unit testing
• all quotas-related features in one place
• avoid storing quotas in AccountData runtime type

And the discussion points become more obvious too.

• on_idle functions should not fail, but we could add events to make it easier to observe that a refund failed (→ is it necessary?)

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• 076c276b - fix actual value of refund fee

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• 5d764200 - add event for linking / unlinking identity

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marked the checklist item automatically link the account of a newly created identity as completed

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• 3a7b25c5 - automatically link account of newly created identity

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changed the description