* Adds transaction_context and instruction_context where invoke_context.get_keyed_accounts() is used.
* Use instruction_context.get_instruction_data() instead of an explicit parameter.
* Removes instruction_data parameter from Executor::execute().
* Removes instruction_data parameter from ProcessInstructionWithContext.
* Adds first_instruction_account parameter to process_instruction().
* Removes InvokeContext::remove_first_keyed_account() from all BPF loaders.
* Removes InvokeContext::remove_first_keyed_account() from all builtin programs.
* Removes InvokeContext::remove_first_keyed_account() from all mock ups.
* Deprecates InvokeContext::remove_first_keyed_account().
* Documents index base of keyed_account_at_index().
* Adds dynamic offset to call sites of "keyed_account_at_index()".
