Add mempool fees to PriceServer getAllMarketPrices endpoint

[ghost]

As mentioned in #5509, Bisq client has two connections to price nodes: FeeService and PriceFeedService. We can optimize Bisq to use PriceFeedService and obtain both sets of information together which provides the following benefits:

• Bisq will use one less network connection and make fewer network API calls,
• corrects the lack of failback mechanism in FeeService,
• increases the frequency of mempool fee updates 5-fold, at no cost.

This change is backwards compatible after PriceNodes are updated:

• old clients can still process getAllMarketPrices and getFees as before.
• new clients can process the additional mempool fee information returned in the getAllMarketPrices data set.

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This change adds two fields: bitcoinFeesTs and bitcoinFeeInfo to getAllMarketPrices:

This PR only modifies the PriceNode. The idea is to give time to get the PriceNodes upgraded before the Bisq client is rolled out (as noted already, the PriceNode upgrade is compatible with existing Bisq clients).

A separate PR will be created for Bisq clients to make use of this PriceNode optimization.

[ghost]

Thanks @KaiWitt changes applied.

[ripcurlx]

utACK