Cleans up the output logs even more. These entries don't add any more
information since everything is grouped now.

Also, make the baseline count message less awkward sounding.

Use strings instead. They are easier to serialize and deserialize.

During the analyze phase.

This commit adds a `packs` option to the codeql-config.yml file. Users
can specify a list of ql packs to include in the analysis.

For a single language analysis, the packs property looks like this:

```yaml
packs:
  - pack-scope/pack-name1@1.2.3
  - pack-scope/pack-name2   # no explicit version means download the latest
```

For multi-language analysis, you must key the packs block by lanaguage:

```yaml
packs:
  cpp:
    - pack-scope/pack-name1@1.2.3
    - pack-scope/pack-name2
  java:
    - pack-scope/pack-name3@1.2.3
    - pack-scope/pack-name4
```

This implementation adds a new analysis run (alongside custom and 
builtin runs). The unit tests indicate that the correct commands are
being run, but I have not actually tried this with a real CLI.

Also, convert `instanceof Array` to `Array.isArray` since that is
sightly better in some situations. See:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray#instanceof_vs_isarray

Fix grouping of the analysis logs, so that custom query logs also get grouped.
Capture the stdout of codeql database analyze, which contains the analysis summary
from summary and diagnostic queries.
Log this output in its own group, along with the baseline computed in the Action.

Fixes a bug where we were looking for incorrect keys for metrics rules.
Previously, we were using full language names in the keys. Now, we use
the short language names in the metric ids. This is done through a
simplification of the code.

Also, this change does two smaller things:

1. Prints out the baseline count to the logs
2. Adds the `assertNever` function to ensure we never miss a case in
   a switch statement. This function is borrowed from vscode-codeql.

The SARIF that we are interpreting has moved away from using `metric`
to the more general term, `rule`. We need to adapt our baseline lines of
code counting to use `rule` as well.

This change passes in a list of file types to the line counting
analysis. These are the languages for the databases being analyzed.
Line count analysis is restricted to these files.

This commit uses a third party library to estimate the lines of code in
a database that is to be analyzed by codeql.

The estimate uses the same includes and excludes globs for determining
which files should be counted.

The lines of code count is returned by language and injected into the
SARIF as `baseline` property in the `${language}/summary/lines-of-code`
metric.

https://github.com/github/codeql-action/pull/323#discussion_r530978010

This flag is already being used for `runQueries`, so let's use it for
finalize as well.