fix(storage): backport read-only FS database support

[shekhirin]

Blocked by #7090

Fixes #6354

➜  reth (alexey/backport-mdbx-ro-fs) hdiutil attach -readonly holesky.dmg
/dev/disk5              GUID_partition_scheme          
/dev/disk5s1            EFI                            
/dev/disk5s2            Apple_HFS                       /Volumes/HOLESKY
➜  reth (alexey/backport-mdbx-ro-fs) sudo ls -lh /Volumes/HOLESKY
total 336
drwx------  17 shekhirin  staff   578B Mar  8 16:23 .fseventsd
drwxr-xr-x@  2 shekhirin  staff    68B Mar  5 17:10 blobstore
drwx---r-x@  5 shekhirin  staff   170B Mar  7 17:25 db
-rw-r--r--@  1 shekhirin  staff    64B Jan  8 15:05 discovery-secret
-rw-r--r--@  1 shekhirin  staff    64B Jan  8 15:05 jwt.hex
-rw-r--r--@  1 shekhirin  staff   152K Mar  5 17:58 known-peers.json
-rw-r--r--@  1 shekhirin  staff   1.7K Jan  8 15:05 reth.toml
drwxr-xr-x@  3 shekhirin  staff   102B Feb 29 14:26 snapshots
drwxr-xr-x@ 29 shekhirin  staff   986B Mar  5 13:06 static_files
➜  reth (alexey/backport-mdbx-ro-fs) sudo ls -lh /Volumes/HOLESKY/db
total 50331656
-rw-rw-r--@ 1 shekhirin  staff     1B Feb 29 14:46 database.version
-rw-rw-r--@ 1 shekhirin  staff    24G Mar  5 17:13 mdbx.dat
-rw-rw-r--@ 1 shekhirin  staff     0B Mar  7 17:30 mdbx.lck
➜  reth (alexey/backport-mdbx-ro-fs) RETH_DB_PATH=/Volumes/HOLESKY target/debug/examples/db-access
➜  reth (alexey/backport-mdbx-ro-fs)