removes contentious usage of mutexes in LRU, which
were never really reused in any manner; we do not
need it.
To trust hosts, the correct way is TLS certs; this PR completely
removes this dependency, which has never been useful.
```
0 0% 100% 25.83s 26.76% github.com/hashicorp/golang-lru/v2/expirable.(*LRU[...])
0 0% 100% 28.03s 29.04% github.com/hashicorp/golang-lru/v2/expirable.(*LRU[...])
```
Bonus: use `x-minio-time` as a nanosecond to avoid unnecessary
parsing logic of time strings instead of using a more
straightforward mechanism.
This change uses the updated ldap library in minio/pkg (bumped
up to v3). A new config parameter is added for LDAP configuration to
specify extra user attributes to load from the LDAP server and to store
them as additional claims for the user.
A test is added in sts_handlers.go that shows how to access the LDAP
attributes as a claim.
This is in preparation for adding SSH pubkey authentication to MinIO's SFTP
integration.
```
==================
WARNING: DATA RACE
Read at 0x0000082be990 by goroutine 205:
github.com/minio/minio/cmd.setCommonHeaders()
Previous write at 0x0000082be990 by main goroutine:
github.com/minio/minio/cmd.lookupConfigs()
```
* Reduce allocations
* Add stringsHasPrefixFold which can compare string prefixes, while ignoring case and not allocating.
* Reuse all msgp.Readers
* Reuse metadata buffers when not reading data.
* Make type safe. Make buffer 4K instead of 8.
* Unslice
