[performance] cached oauth database types (#2838)

* update token + client code to use struct caches

* add code comments

* slight tweak to default mem ratios

* fix envparsing

* add appropriate invalidate hooks

* update the tokenstore sweeping function to rely on caches

* update to use PutClient()

* add ClientID to list of token struct indices

internal/cache/cache.go

@@ -59,6 +59,7 @@ func (c *Caches) Init() {
 	c.initBlock()
 	c.initBlockIDs()
 	c.initBoostOfIDs()
+	c.initClient()
 	c.initDomainAllow()
 	c.initDomainBlock()
 	c.initEmoji()
@@ -85,9 +86,10 @@ func (c *Caches) Init() {
 	c.initReport()
 	c.initStatus()
 	c.initStatusFave()
+	c.initStatusFaveIDs()
 	c.initTag()
 	c.initThreadMute()
-	c.initStatusFaveIDs()
+	c.initToken()
 	c.initTombstone()
 	c.initUser()
 	c.initWebfinger()