Exclusion of source fields

[scampi]

This PR adds filtering capability of source fields for a given index pattern. Excluded fields are then not retrieved by a saved search. However, looking at a document using the doc API displays all available fields.

In the index settings, a new column excluded is added which indicates if a field is excluded or not. In the picture, the born field is excluded. There is also a new tab source filters which shows all the exclusion patterns.

Below is the source filters tab which shows on the left side the filter pattern, as well as the fields that match.

On the discover page, I had created a saved search showing the field born. It is now empty since it is excluded.

However, if you look at a specific document, all available fields are displayed.

close #4366.
Reimplementation of #5981.

[elasticsearch-release]

Jenkins standing by to test this. If you aren't a maintainer, you can ignore this comment. Someone with commit access, please review this and clear it for Jenkins to run; then say 'jenkins, test it'.

[scampi]

Errors in jenkins seem unrelated to this PR. I see many of the following:

TypeError: _this.saveScreenshot(...).finally is not a function
  at Command.<anonymous>  <test/support/pages/common.js:259:17>
  at runCallback  <node_modules/intern/node_modules/leadfoot/Command.js:526:31>
  at Command.<anonymous>  <node_modules/intern/node_modules/leadfoot/Command.js:545:11>
  at <node_modules/intern/node_modules/dojo/Promise.ts:393:15>
  at run  <node_modules/intern/node_modules/dojo/Promise.ts:237:7>
  at <node_modules/intern/node_modules/dojo/nextTick.ts:44:3>
  at nextTickCallbackWith0Args  <node.js:420:9>
  at process._tickCallback  <node.js:349:13>
  at Command.then  <node_modules/intern/node_modules/leadfoot/Command.js:542:10>
  at Command.catch  <node_modules/intern/node_modules/leadfoot/Command.js:556:15>
  at Test.test  <test/functional/apps/discover/_shared_links.js:132:17>
  at <node_modules/intern/lib/Test.js:211:24>
  at <node_modules/intern/node_modules/dojo/Promise.ts:393:15>
  at runCallbacks  <node_modules/intern/node_modules/dojo/Promise.ts:11:11>
  at <node_modules/intern/node_modules/dojo/Promise.ts:317:4>
  at run  <node_modules/intern/node_modules/dojo/Promise.ts:237:7>
  at <node_modules/intern/node_modules/dojo/nextTick.ts:44:3>
  at nextTickCallbackWith0Args  <node.js:420:9>
  at process._tickCallback  <node.js:349:13>

[LeeDr]

The first failure screenshot shows this;

The test failed to find the toast message "Discover: Saved Data Source "Query # 1" even though it is there, because there's another toast error message that says "! Discover: this.fieldFilters is undefined".

I haven't figured out why that message is being displayed. But it looks like it might be related to this PR.

[spalger]

jenkins, test this

[spalger]

@Bargs can you take another look at this?

[Bargs]

Just one last thought:

Note that multi-fields will incorrectly appear as matches in the table below. These filters only actually apply to fields in the original source document, so matching multi-fields are not actually being filtered.

Now that we're putting this front and center, I think we should remove the special treatment of .raw and .keyword fields. Then at least our descriptive text and code will be consistent and hopefully less magical/confusing to users who are trying to understand how this works.

[scampi]

@Bargs I removed the logic about raw and keyword fields.

[Bargs]

LGTM. How about you @spalger ?

[spalger]

big +1, LGTM!

[Bargs]

🎉 🎉 🎉 🎉

[epixa]

@scampi Thanks for sticking with this PR to the end. This will help a lot of people.