[CBR-255] Full version of 'getTxMeta'
[CBR-255] Full version of 'getTxMeta'

This commit removes the placeholders from the 'getTxMeta' function,
using the full power of the Beam SQL DSL to rebuild a kernel's 'TxMeta'
out of a SQL-scattered relational data.

input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/cardano-sl