Add Error message when sync is still in progress. (#9475)

* closes #9188

* check_for_unavailable_block in
eth_getTransactionByHash
eth_getTransactionByBlockHashAndIndex
eth_getTransactionByBlockNumberAndIndex
eth_getTransactionReceipt

* check for unavailable block in eth_getBlockByNumber

* corrected checks for unavailable_block

* check for block gaps in db

* corrected error messages

* corrected error information

* added allow-empty-block-result cli flag

* address grumbles

* --jsonrpc-allow-missing-blocks

* fix tests

* added checks to
    block_transaction_count_by_hash
    block_transaction_count_by_number
    block_uncles_count_by_hash
    block_uncles_count_by_number
    uncle_by_block_hash_and_index
    uncle_by_block_number_and_index
fix PR grumbles

* Update parity/cli/mod.rs

revert config name

Co-Authored-By: seunlanlege <seunlanlege@gmail.com>

* Update parity/cli/mod.rs

revert cli arg

Co-Authored-By: seunlanlege <seunlanlege@gmail.com>

* Apply suggestions from code review

revert config name

Co-Authored-By: seunlanlege <seunlanlege@gmail.com>

* fix PR grumbles

* fix more PR grumbles

parity/cli/tests/config.full.toml

@@ -64,6 +64,7 @@ interface = "local"
 cors = ["null"]
 apis = ["web3", "eth", "net", "parity", "traces", "rpc", "secretstore"]
 hosts = ["none"]
+allow_missing_blocks = false
 
 [websockets]
 disable = false