[ML] Moves URL, interval and ordinal ui utils into ML

[peteharverson]

Summary

As part of the migration to the new platform, copies several utility functions which were previously from the legacy ui folder into the ML codebase:

• ui/url/relative_to_absolute (copied as-is into new ML util/url_utils)
• ui/utils/ordinal_suffix (added new ML formatters/number_as_ordinal which uses the numeral.js ordinal format
• ui/utils/parse_interval (switched all ML code to use the existing ML common/util/parse_interval

Also removed unused ui/kbn_top_nav import from app.js.

Note that the ML common/util/parse_interval differs from the legacy ui/utils/parse_interval in the following ways:

1. A value-less interval such as 'm' is not allowed - in line with the ML back-end not accepting such interval Strings for the bucket span of a job.
2. Zero length durations 0ms, 0s, 0m and 0h are accepted as-is. Note the job wizard implements a separate check that the bucket span is not zero length.
3. Fractional intervals e.g. 1.5h or 4.5d are not allowed, in line with the behavior of the Elasticsearch date histogram aggregation.

Checklist

• This was checked for cross-browser compatibility, including a check against IE11
• Unit or functional tests were updated or added to match the most common scenarios

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[jgowdyelastic]

LGTM

[darnautov]

LGTM

[walterra]

LGTM

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 5966850

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: c5c35c5