Add initial support for isIndexed

[timleslie]

Add an isIndexed config option to the text, integer, float, select, and timestamp field types.

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🦋 Changeset detected

Latest commit: b08b67e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@keystone-next/keystone	Minor
@keystone-next/fields	Minor
@keystone-next/adapter-prisma-legacy	Minor
@keystone-next/test-utils-legacy	Patch
@keystone-next/auth	Major
@keystone-next/example-auth	Patch
@keystone-next/app-basic	Patch
@keystone-next/example-ecommerce	Patch
keystone-next-app	Patch
@keystone-next/example-roles	Patch
@keystone-next/example-sandbox	Patch

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[emmatown]

Aren't you reading isIndexed from the adapter, not the implementation class? So this is doing nothing? but it still works because isIndexed is already set on the adapter class?