Fix internal type definition for session delegates

[imjoehaines]

Goal

The internal type definition for session delegates was wrong in a few ways:

• startSession returned any when it should always return a client
• pauseSession took no parameters when it actually takes a client
• resumeSession took no parameters and returned void when it actually takes and returns a client

This can be verified by checking the session implementations:

• plugin-browser-session (plugin-electron-session uses this implementation internally)
• plugin-react-native-session
• plugin-server-session

There are no BC concerns here as we don't ship this type definition file in the NPM package, it's purely used internally:

bugsnag-js/packages/core/package.json

Lines 15 to 19 in ce9d8dc

	"files": [
	"lib",
	"types",
	"*.js"
	],

[github-actions]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	41.24 kB	12.71 kB
After	41.24 kB	12.71 kB
±	No change	No change

code coverage diff

Coverage values did not change👌.

Total:

Lines	Branches	Functions	Statements
0%(+0%)	0%(+0%)	0%(+0%)	0%(+0%)

Generated by 🚫 dangerJS against ce9d8dc