implements different disk sizes for different networks on intro

- Creates m_assumed_blockchain_size and m_assumed_chain_state_size on CChainParams.
- Implements access to CChainParams' m_assumed_blockchain_size and m_assumed_chain_state_size on node interface.
- Implements m_assumed_blockchain_size and m_assumed_chain_state_size on qt/intro via node interface.
- Updates release process document with the new CChainParam's values.

src/interfaces/node.h

@@ -52,6 +52,12 @@ public:
     //! Choose network parameters.
     virtual void selectParams(const std::string& network) = 0;
 
+    //! Get the (assumed) blockchain size.
+    virtual uint64_t getAssumedBlockchainSize() = 0;
+
+    //! Get the (assumed) chain state size.
+    virtual uint64_t getAssumedChainStateSize() = 0;
+
     //! Get network name.
     virtual std::string getNetwork() = 0;