feat(bin): expose db.table_entries metric

[shekhirin]

Tested on my local syncing Sepolia node:

➜  ~  curl -s localhost:9001 | grep table_entries
# TYPE reth_db_table_entries counter
reth_db_table_entries{table="StoragesTrie"} 0
reth_db_table_entries{table="SyncStageProgress"} 0
reth_db_table_entries{table="BlockWithdrawals"} 0
reth_db_table_entries{table="AccountsTrie"} 0
reth_db_table_entries{table="BlockBodyIndices"} 1950001
reth_db_table_entries{table="PruneCheckpoints"} 0
reth_db_table_entries{table="BlockOmmers"} 49770
reth_db_table_entries{table="HeaderNumbers"} 2000001
reth_db_table_entries{table="StorageChangeSet"} 0
reth_db_table_entries{table="Receipts"} 0
reth_db_table_entries{table="Transactions"} 2452236
reth_db_table_entries{table="CanonicalHeaders"} 2000001
reth_db_table_entries{table="StorageHistory"} 0
reth_db_table_entries{table="HashedAccount"} 15
reth_db_table_entries{table="HeaderTD"} 2000001
reth_db_table_entries{table="TransactionBlock"} 475487
reth_db_table_entries{table="Headers"} 2000001
reth_db_table_entries{table="AccountChangeSet"} 15
reth_db_table_entries{table="PlainAccountState"} 15
reth_db_table_entries{table="PlainStorageState"} 0
reth_db_table_entries{table="HashedStorage"} 0
reth_db_table_entries{table="SyncStage"} 13
reth_db_table_entries{table="TxSenders"} 0
reth_db_table_entries{table="Bytecodes"} 0
reth_db_table_entries{table="TxHashNumber"} 0
reth_db_table_entries{table="AccountHistory"} 15

[codecov]

Codecov Report

Merging #4316 (2a58748) into main (8d25aa3) will increase coverage by 0.02%.
Report is 2 commits behind head on main.
The diff coverage is 0.00%.

Files Changed	Coverage Δ
bin/reth/src/prometheus_exporter.rs	0.00% <0.00%> (ø)

... and 10 files with indirect coverage changes

Flag	Coverage Δ
integration-tests	16.83% <0.00%> (-0.01%)	⬇️
unit-tests	63.78% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
reth binary	26.11% <0.00%> (-0.01%)	⬇️
blockchain tree	82.56% <ø> (ø)
pipeline	90.07% <ø> (ø)
storage (db)	74.77% <ø> (ø)
trie	94.85% <ø> (ø)
txpool	48.71% <ø> (+0.51%)	⬆️
networking	77.53% <ø> (+<0.01%)	⬆️
rpc	58.81% <ø> (ø)
consensus	63.53% <ø> (ø)
revm	32.01% <ø> (ø)
payload builder	6.82% <ø> (ø)
primitives	86.15% <ø> (-0.02%)	⬇️