1.9.0 preview

* identity: allow creating a role with a non-existent key

* remove whitespace

* add changelog

* Updating go version to 1.16.6 for security fix

* Changelog

* Add link to Learn's usage tutorial

* Update website/content/docs/commands/operator/usage.mdx
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>

This functionality was introduced in Vault 1.7.0 and is documented in api-docs/system/rotate-config

* fixes helperTextDisabled/Enabled

* modified toc

* relocated vault integration program section

* serviceregistration: add external-source meta value

* add changelog file

* oss part of license diagnose test fix

* cl

* save

* fix diagnose formatting errors

* fix diagnose formatting errors

* change powers

* change powers

* use humanize instead of doing the conversion to mb manually

* cl

* Improve "Integrated Storage" documentation

* add missing markup
* add more links to the configuration pages

* Improve the Raft Storage configuration page

* More markup

* Improve the "High Availability" documentation

* More links to the configuration pages

* More links

* even more links

* VAULT-1303 when a request to vault fails, show namespace if set

* Adding changelog

* Fix Changelog file name

* Set namespace in ResponseWriter headers if it is set

* Using consts.NamespaceHeaderName instead of the literal string

* adds await settled

And found a couple missing values

* match style

* add gap after talking with design

* Update docs to reflect support for autopilot DR

* Reword sentence

* Fix link

* Fix link

* do not allow token_ttl to be longer than verification_ttl

* add verification when updating an existing key

When updating a key, ensure any roles referencing the key do not already
have a token_ttl greater than the key's verification_ttl

* add changelog

* remove unneeded UT check and comment

* refactor based on PR comments

- remove make slice in favor of var delcaration
- remove unneeded if check
- validate expiry value during token generation
- update changelog as bug

* refactor get roles referencing target key names logic

* add note about thread safety to helper func

* update func comment

* sort array and refactor func names

* add warning to return response

* remove unnecessary code from unit test

* Update vault/identity_store_oidc.go
Co-authored-by: Austin Gebauer <34121980+austingebauer@users.noreply.github.com>
Co-authored-by: Austin Gebauer <34121980+austingebauer@users.noreply.github.com>

* [NO-TICKET] Set protoc-gen-go to 1.23, upgrade protoc to 3.17.3

* [NO-TICKET] Upgrade version of protoc-gen-go to 1.26

* Docs: Fix broken link

What does this PR do

Fix dead or broken links in this docs page, making navigation easy for others.

* fixing broken link

* fixing broken links

Deleted duplicate text

Co-authored-by: Yoko Hyakuna <yoko@hashicorp.com>