Default values for list/set query&header params

[pnepywoda]

Handle adding default query/header list/set parameters without breaking function callers

Fix #615

[changelog-app[bot]]

Generate changelog in changelog-dir>`changelog/@unreleased`</changelog-dir

Type

- [ ] Feature - [x] Improvement - [ ] Fix - [ ] Break - [ ] Deprecation - [ ] Manual task - [ ] Migration

Description

Default values for list/set query&header params Handle adding default query/header list/set parameters without breaking function callers **Check the box to generate changelog(s)** - [x] Generate changelog entry

[pnepywoda]

https://github.com/palantir/conjure-python/pull/617