Better handling for missing transactions in history_plugin

[wanderingbort]

• modified history_plugin to throw when the transaction is not found instead of returning a meaningless structure
• modified history_plugin to accept a block_num_hint optionally which is used to fetch transactions from the block log without any history data
• created help text for get transaction that better explains the error and suggests solutions

resolves #3887

# given trx ce8fb4a99dedc1dff52eab790df97ddb2a49c45ac396b8f4a978e31468a7819b 
# in block 100 but not in the history_plugin --filter-on parameter

$ cleos get transaction ce8fb4a99dedc1dff52eab790df97ddb2a49c45ac396b8f4a978e31468a7819b
Failed to fetch information for transaction: ce8fb4a9 from the history plugin

If you know the block number which included this transaction you providing it with the --block-hint option may help
Please ensure that the eosio::history_plugin is enabled on the RPC node you are connecting to and that an account involved in this transaction was configured in the filter-on setting.

$ cleos get transaction ce8fb4a99dedc1dff52eab790df97ddb2a49c45ac396b8f4a978e31468a7819b -b 500000
Failed to fetch information for transaction: ce8fb4a9 from the history plugin and the transaction was not present in block 500000

Please ensure that the eosio::history_plugin is enabled on the RPC node you are connecting to and that an account involved in this transaction was configured in the filter-on setting.

$ cleos get transaction ce8fb4a99dedc1dff52eab790df97ddb2a49c45ac396b8f4a978e31468a7819b -b 100
<snip transaction information w/o tracing if the history_plugin had no data>

[wanderingbort]

I merged in the seemingly unrelated fix for #4145, which makes this a PR that will auto close #4146
However, this should fix the test cases.