Improve LocalRest to see which call triggered an assertion failure

[Geod24]

Currently, if a node assert in unittest, we'll see something like this:

[...]
Unittesting agora.test.VariableBlockSize..
Unittesting agora.test.ValidatorRecurringEnrollment..
================================ ASSERT HANDLER ===============================
[source/agora/node/Ledger.d:351] Assertion thrown during test:
/Users/geod24/projects/bpfk/agora/source/agora/node/Ledger.d:351 @safe bool agora.node.Ledger.Ledger.acceptTransaction(agora.consensus.data.Transaction.Transaction) [0x10fd9cfdd]
/Users/geod24/projects/bpfk/agora/source/agora/node/FullNode.d:712 @safe void agora.node.FullNode.FullNode.putTransaction(agora.consensus.data.Transaction.Transaction) [0x10fe091b7]
/Users/geod24/projects/bpfk/agora/source/agora/test/Base.d:1583 @safe void agora.test.Base.TestValidatorNode.__mixin8.putTransaction(agora.consensus.data.Transaction.Transaction) [0x10fd40730]
/Users/geod24/projects/bpfk/agora/submodules/localrest/source/geod24/LocalRest.d-mixin-667:684 void geod24.LocalRest.RemoteAPI!(agora.test.Base.TestAPI, agora.test.Base.Serializer).RemoteAPI.handleCommand(geod24.LocalRest.Command, agora.test.Base.TestAPI, geod24.LocalRest.FilterAPI, geod24.concurrency.Channel!(geod24.LocalRest.Response).Channel) [0x10fe0e7bf]
/Users/geod24/projects/bpfk/agora/submodules/localrest/source/geod24/LocalRest.d:801 void geod24.LocalRest.RemoteAPI!(agora.test.Base.TestAPI, agora.test.Base.Serializer).RemoteAPI.spawned!(agora.test.Base.TestValidatorNode).spawned(geod24.concurrency.Channel!(geod24.LocalRest.Connection).Channel, immutable(char)[], int, agora.common.Config.Config, shared(geod24.Registry.Registry!(agora.test.Base.TestAPI).Registry)*, shared(geod24.Registry.Registry!(agora.registry.API.NameRegistryAPI).Registry)*, immutable(agora.consensus.data.Block.Block)[], in ref agora.test.Base.TestConf, shared(ulong)*).runNode().__lambda1().__lambda4() [0x10fe2e8a4]
context.d:46 void core.thread.context.Callable.opCall() [0x110d6518e]
fiber.d:1129 void core.thread.fiber.Fiber.run() [0x110d6531d]
fiber.d:186 fiber_entryPoint [0x110d65252]
================================ NODE LOGS ===============================
2021-04-18 19:48:21,460 Info [agora.node.Ledger] - Last known block: #0 (0x1f11e6c77f54030baf04b0fada789e5a34f6fab36d1377acd697788b561eb0b7acb469c13b54934516c9fd2ea279603a92e1d2078f33a922c6bb7d3c43df8cf0)
2021-04-18 19:48:21,463 Info [agora.node.Ledger] - Beginning externalization of block #0
2021-04-18 19:48:21,463 Info [agora.node.Ledger] - Transactions: 2 - Enrollments: 6
2021-04-18 19:48:21,463 Info [agora.node.Ledger] - Validators: Active: 0 - Signing: [0] - Slashed: []
[...]

Provided https://github.com/bosagora/agora/pull/1971 is merged. The issue with this is that we don't know which call in the unittest itself triggered the assertion, which makes it hard to follow the logic.