Add feature flag for reusable services integration

[IvanKavaldzhiev]

Problem

The integration of reusable services will span through multiple releases and will be delivered in chunks. That's why we need a feature flag to disable the new code before it's fully implemented and properly tested.

Solution

We can define a feature flag that will control which flow to be used (old mono code base or new reusable services code
base). The deviation point will be inside ContractCallService.doProcessCall, where:

• if the feature flag is enabled, we will call the new TransactionExecutor.execute method
• if the feature flag is disabled, we will call the MirrorEvmTxProcessor.execute method

To call the new TransactionExecutor.execute we need to transform the request parameters into the needed transaction body from the package com.hedera.hapi.node. Also, the existing integration tests might need to be adjusted to use this flag and this new way of transaction body construction as well.

After the new code base is fully integrated and tested, we will remove the old mono code base and the feature flag.

Alternatives

No response