[Jah-yee]

Description

Fixes #2442.

The outlier detection load balancer config parser only accepted the internal
object form of a Duration ({seconds, nanos}). The canonical protobuf JSON
representation of a Duration is a string such as "10s", so a config using the
standard representation was rejected with:

outlier detection config interval parse error: expected Duration, got string

This makes the outlier_detection LB policy unusable with canonical JSON
config, while other duration-bearing policies in this repo
(weighted_round_robin) already accept the string form.

Change

packages/grpc-js/src/load-balancer-outlier-detection.ts

• Add parseDurationValue(), which accepts the canonical string form
  ("10s", "1.5s"), the DurationMessage form ({seconds: "10", nanos: 0}),
  and the existing internal object form ({seconds: 10, nanos: 0}).
• validatePositiveDuration() now returns the parsed Duration, and range
  validation is performed against that parsed value rather than the raw input.
• createFromJson() uses the parsed durations when converting to milliseconds,
  so interval, base_ejection_time and max_ejection_time all honour the
  canonical representation.

The existing object form remains fully supported, so this is backwards
compatible.

Testing

packages/grpc-js/test/test-outlier-detection.ts

Added tests covering the canonical string form (including a fractional value),
the DurationMessage form, the pre-existing object form, and rejection of an
unparseable duration string.

$ npm install
$ npx tsc -p .
$ npx mocha build/test/test-outlier-detection.js
  32 passing

All 26 pre-existing tests in that file still pass.