Maximum number of account info structs that can be used in a single CPI
invocation. A limit on account info structs is effectively the same as
limiting the number of unique accounts. 128 was chosen to match the max
number of locked accounts per transaction (MAX_TX_ACCOUNT_LOCKS).
Maximum CPI instruction accounts. 255 was chosen to ensure that instruction
accounts are always within the maximum instruction account limit for BPF
program instructions.
Maximum CPI instruction data size. 10 KiB was chosen to ensure that CPI
instructions are not more limited than transaction instructions if the size
of transactions is doubled in the future.