Add block height to ConfirmedBlock structs (#17523)

* Add BlockHeight CF to blockstore

* Rename CacheBlockTimeService to be more general

* Cache block-height using service

* Fixup previous proto mishandling

* Add block_height to block structs

* Add block-height to solana block

* Fallback to BankForks if block time or block height are not yet written to Blockstore

* Add docs

* Review comments

core/src/bigtable_upload_service.rs

@@ -8,10 +8,10 @@ use std::{
 use tokio::runtime::Runtime;
 
 // Delay uploading the largest confirmed root for this many slots.  This is done in an attempt to
-// ensure that the `CacheBlockTimeService` has had enough time to add the block time for the root
+// ensure that the `CacheBlockMetaService` has had enough time to add the block time for the root
 // before it's uploaded to BigTable.
 //
-// A more direct connection between CacheBlockTimeService and BigTableUploadService would be
+// A more direct connection between CacheBlockMetaService and BigTableUploadService would be
 // preferable...
 const LARGEST_CONFIRMED_ROOT_UPLOAD_DELAY: usize = 100;