[7.x] [Discover] Allow custom name for fields via index pattern field management (#70039)

[kertal]

Backports the following commits to 7.x:

• [Discover] Allow custom name for fields via index pattern field management ([Discover] Allow custom label for fields via index pattern field management #70039)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: a01bf9e

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
discover	274	273	-1

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
discover	422.0KB	422.1KB	+73.0B
indexPatternManagement	609.9KB	611.7KB	+1.8KB
total			+1.9KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
data	967.1KB	968.6KB	+1.4KB
discover	82.1KB	82.0KB	-116.0B
total			+1.3KB

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream