Align eth_getStorageAt parameter validation with Ethereum's OpenRPC specification #3839

[se7enarianelabs]

hiero-ledger/hiero-json-rpc-relay#3839 (comment)

[mwb-al]

hiero-ledger/hiero-json-rpc-relay#3839 (comment)
Luis mentioned that blockNumberOrTagOrHash is a custom field and it should be possible to set it to null

[mwb-al]

issue: hiero-ledger/hiero-json-rpc-relay#3839

pr: hiero-ledger/hiero-json-rpc-relay#3879

[mwb-al]

@arianejasuwienas approved