[GRPH-111] Added get_asset_count API

[srpatel19590]

An API call that can return the total number of assets available. This will be used to get rid of loading assets on UI

[bobinson]

Provide steps for the QA to

• create asset
• test from the cli_wallet

[oxarbitrage]

looks good, thanks.

[srpatel19590]

Testing procedure:

• connect cli_wallet to peerplays node
• get current asset count by get_asset_count
• create new asset using create_asset
• get new asset count by get_asset_count . It should be incremented by 1.

[srpatel19590]

Example cli commands

• Get current asset count

unlocked >>> get_asset_count
get_asset_count
1

• Create new asset
  create_asset "1.2.18" "DIV" 5 {"max_supply" : 10000000000,"market_fee_percent" : 0,"max_market_fee" : 10000000000,"issuer_permissions" : 79,"flags" : 0,"core_exchange_rate" : {"base": {"amount": 1,"asset_id": "1.3.0"},"quote": {"amount": 1,"asset_id": "1.3.1"}},"whitelist_authorities" : [],"blacklist_authorities" : [],"whitelist_markets" : [],"blacklist_markets" : [],"description" : "Bitcoin with precision 8"} {} true

• Get asset count again

unlocked >>> get_asset_count
get_asset_count
2