Add preflight checks to sendTransaction RPC method

[mvines]

sendTransaction blindly dumps the transaction it receives into a TPU. It can do better by:

1. Verify transaction signatures
2. Simulating the transaction against the latest max confirmed bank
   and on failure, return an error to the caller. If the RPC node is unhealthy it will refuse to run the simulation

Preflight checks may be disabled if desired with sendTransaction's new config input parameter. By default they are enabled for the convenience of existing API users.

Towards #10336

[mvines]

@CriesofCarrots - I think this is ready for review. Mostly just playing whack-a-test right now, in some places like program deploy where we (currently) intentionally don't wait for max confirmation between the different phases of deployment and thus the new default sendTransaction preflight checks will fail.

[mvines]

(also CI is being a 🐻)

[CriesofCarrots]

Nice, this looks good to me, pending tests. And (note to self) now that the trusted validators are available in JsonRpcRequestProcessor via health, it will be straightforward to address #9882

Pull request has been modified.

[mvines]

Added test_rpc_send_transaction_preflight() to cover all the preflight branches

[codecov]

Codecov Report

Merging #10338 into master will increase coverage by 0.1%.
The diff coverage is 89.7%.

@@            Coverage Diff            @@
##           master   #10338     +/-   ##
=========================================
+ Coverage    81.3%    81.4%   +0.1%     
=========================================
  Files         288      289      +1     
  Lines       67150    67315    +165     
=========================================
+ Hits        54607    54811    +204     
+ Misses      12543    12504     -39     

[mvines]

OMG finally got through CI.