* initial prometheus sketch

need env variable to start: MB_PROMETHEUS_SERVER_PORT=9191

sample of output:

```
'# HELP jvm_threads_current Current thread count of a JVM
'# TYPE jvm_threads_current gauge
jvm_threads_current 81.0
'# HELP jvm_threads_daemon Daemon thread count of a JVM
'# TYPE jvm_threads_daemon gauge
jvm_threads_daemon 36.0
'# HELP jvm_threads_peak Peak thread count of a JVM
'# TYPE jvm_threads_peak gauge
jvm_threads_peak 81.0
'# HELP jvm_threads_started_total Started thread count of a JVM
'# TYPE jvm_threads_started_total counter
jvm_threads_started_total 104.0
'# HELP jvm_threads_deadlocked Cycles of JVM-threads that are in deadlock waiting to acquire object monitors or ownable synchronizers
'# TYPE jvm_threads_deadlocked gauge
jvm_threads_deadlocked 0.0
```

request:

```
❯ http localhost:9191/metrics
HTTP/1.1 200 OK
Content-Length: 7329
Content-Type: text/plain; version=0.0.4; charset=utf-8
Date: Wed, 31 Aug 2022 16:13:38 GMT
Server: Jetty(9.4.48.v20220622)

'# HELP jvm_gc_collection_seconds Time spent in a given JVM garbage collector in seconds.
'# TYPE jvm_gc_collection_seconds summary
jvm_gc_collection_seconds_count{gc="G1 Young Generation",} 41.0
jvm_gc_collection_seconds_sum{gc="G1 Young Generation",} 0.586
jvm_gc_collection_seconds_count{gc="G1 Old Generation",} 0.0
jvm_gc_collection_seconds_sum{gc="G1 Old Generation",} 0.0
'# HELP jvm_threads_current Current thread count of a JVM
'# TYPE jvm_threads_current gauge
```

* Log on unparseable prometheus port

* Clean up prometheus and save test

* typehint

* Jetty collector

* Reset system to nil when shutting down

* c3p0 stats

* Clean up, document, and add tests

* Error message for failure to bind to port

Starting up with prometheus port set to the main webserver port to get
the error:

```
MB_JETTY_PORT=3006 MB_DB_CONNECTION_URI="postgres://..." \
MB_PROMETHEUS_SERVER_PORT=3006 java -jar locally-built.jar
```
yields the following error:

```shell
2022-09-09 10:08:52,000 INFO metabase.core :: Setting up prometheus metrics
2022-09-09 10:08:52,002 INFO metabase.prometheus :: Starting prometheus metrics collector
2022-09-09 10:08:52,016 INFO metabase.prometheus :: Starting prometheus metrics web-server on port 3,006
2022-09-09 10:08:52,036 ERROR metabase.core :: Metabase Initialization FAILED
clojure.lang.ExceptionInfo: Failed to initialized Prometheus on port 3,006 {:port 3006}
[stacktrace ...]
Caused by: java.io.IOException: Failed to bind to 0.0.0.0/0.0.0.0:3006
[stacktrace ...]
Caused by: java.net.BindException: Address already in use
```

* Test for error message

* Move prometheus to analytics folder

* Str port so log does not add commas to number

eg:
> Starting prometheus metrics web-server on port 9,191

* make some test functions private

* docstring on defsetting

* align lets

* ns docstring changes

include the env variable for ease of understanding

* sort ns

* remove some reflection warnings

* reorder FE lines due to some new linter

* Cleanup: i18n descriptions, typo, List/of

* bit more concise c3p0 collection

* no longer need the helper `->array`

* clean up doseq for c3p0 measurements