[ML] Versioning transforms APIs

[jgowdyelastic]

Adds versioning to all of the transform APIs.
Versions are added to the server side routes and to the client side functions which call the routes.
Updates API tests to add the API version to the request headers.

All of the APIs are internal and have been given the version '1'.

Internal APIs

/internal/transform/privileges
/internal/transform/field_histograms/{dataViewTitle}
/internal/transform/privileges
/internal/transform/transforms/{transformId}/messages
/internal/transform/transforms/_nodes
/internal/transform/transforms
/internal/transform/transforms/{transformId}
/internal/transform/transforms/_stats
/internal/transform/transforms/{transformId}/_stats
/internal/transform/transforms/{transformId}
/internal/transform/transforms/{transformId}/_update
/internal/transform/reauthorize_transforms
/internal/transform/delete_transforms
/internal/transform/reset_transforms
/internal/transform/transforms/_preview
/internal/transform/start_transforms
/internal/transform/stop_transforms
/internal/transform/schedule_now_transforms

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[qn895]

nit: Since we are not validating here, we can change this to validate: false?

[jgowdyelastic]

I wasn't 100% sure if validate: {} is identical to validate: false so left this with no changes.
But it's very low risk, so I'll change it.

[jgowdyelastic]

Updated in e8cfb92

[peteharverson]

Code LGTM

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 8820468

Metrics [docs]

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
esUiShared	110	111	+1

Async chunks

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

id	before	after	diff
transform	387.1KB	387.5KB	+426.0B

Page load bundle

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

id	before	after	diff
esUiShared	152.4KB	152.5KB	+42.0B
transform	17.7KB	17.7KB	+12.0B
total			+54.0B

Unknown metric groups

API count

id	before	after	diff
esUiShared	114	115	+1

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	19	21	+2
securitySolution	400	404	+4
total			+6

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	20	22	+2
securitySolution	480	484	+4
total			+6

History

• 💛 Build #129909 was flaky fbb0ffd
• 💚 Build #129855 succeeded c0701cd
• 💛 Build #129782 was flaky 215bdfa
• 💛 Build #129686 was flaky e8cfb92
• 💚 Build #129652 succeeded 33cfe9e
• 💔 Build #129617 failed 5e3fb85

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

cc @jgowdyelastic

[ElenaStoeva]

Changes to shared useRequest and sendRequest functions LGTM.