[APM] Transaction page throws unhandled exception if transactions doesn't have http.request

[hmdhk]

Kibana version: 8.0.0 snapshot

Elasticsearch version: 8.0.0 snapshot

Describe the bug:
The APM UI can't show transactions that have transaction.http but not transaction.http.request. More specifically this part of code fails and the APM UI structure disappears.

The reason that these transactions can be reported is because of the transaction.context.response proposal which introduces using transaction.context.response for RUM specific metrics.

Steps to reproduce:
0. Build a Chrome extension that injects the RUM agent into a website ;)

1. Go to wikipedia.org to capture a RUM transaction
2. Go to the transaction page

Expected behavior:
Show the transaction.

Errors in browser console (if relevant):

TypeError: Cannot read property 'method' of undefined
    at getTransactionResultSummaryItem (apm.bundle.js:3)
    at TransactionSummary (apm.bundle.js:3)
    at hg (vendors.bundle.dll.js:218)
    at Tg (vendors.bundle.dll.js:218)
    at bi (vendors.bundle.dll.js:218)
    at ci (vendors.bundle.dll.js:218)
    at Di (vendors.bundle.dll.js:218)
    at Yh (vendors.bundle.dll.js:218)
    at Xh (vendors.bundle.dll.js:218)
    at qf (vendors.bundle.dll.js:218)

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[sorenlouv]

Sounds like http.request should be optional then:

kibana/x-pack/legacy/plugins/apm/typings/es_schemas/raw/fields/Http.ts

Lines 7 to 11 in 618e704

	export interface Http {
	request: { method: string; [key: string]: unknown };
	response?: { status_code: number; [key: string]: unknown };
	version?: string;
	}

@jahtalab Is this the case for http.request on both errors and transactions?