v4.1: Bank::get_slot_history() is fallible (backport of #12598)

[mergify]

Problem

Bank::get_slot_history() double unwraps, which causes a panic on error. Instead, let the caller decide if this error is fatal or not.

Summary of Changes

• Makes Bank::get_slot_history() return an Option
• Updates callers to call .unwrap() (this maintains the current behavior--happy to adjust!)
• Add a new RPC error

  ---

  This is an automatic backport of pull request Bank::get_slot_history() is fallible #12598 done by Mergify.

[mergify]

If this PR represents a change to the public RPC API:

1. Make sure it includes a complementary update to rpc-client/ (example)
2. Open a follow-up PR to update the JavaScript client @solana/kit (example)

Thank you for keeping the RPC clients in sync with the server API @mergify[bot].

[codecov-commenter]

Codecov Report

❌ Patch coverage is 52.63158% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.3%. Comparing base (da33332) to head (de60a56).

Additional details and impacted files

@@           Coverage Diff           @@
##             v4.1   #12628   +/-   ##
=======================================
  Coverage    83.3%    83.3%           
=======================================
  Files         851      851           
  Lines      324140   324149    +9     
=======================================
+ Hits       270041   270055   +14     
+ Misses      54099    54094    -5     

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