Add 'context' parameter to init and render functions

[wz2b]

This fixes #23 by:

• Adding a 'context' variable that is initially populated as an empty object then passed to both 'init' and 'render' functions

In addition to this:

• Upgraded to the 8.1.1 grafana toolkit
• Locked the grafana data, ui, and toolkit dependencies to 8.1.1 - the version matters less than the fact that they are all forced to be the same
• Modified the way the component styles (in both the panel and the options) to avoid some things that are deprecated in emotion

Note that the version of emotion being used is 10.0.27 to be compatible with the latest grafana starter example. Using emotion 11 won't work at this time (there are some deprecations and breaking changes). All other upgrades worked fine.

Dependency changes

Bundled:	dependency	old version	upgraded to
emotion	10.0.27	(no change)
@grafana/runtime	^7.1.1	^8.1.1 [SEE NOTE BELOW]
@monaco-editor/react	^3.3.0	^4.2.2
@svgdotjs/svg.js	^3.0.16	^3.1.1
css-loader	^3.5.3	^6.2.0
monaco-editor-webpack-plugin	^1.9.0	^4.1.1
react-monaco-editor	^0.36.0	^0.44.0

Dev/runtime:	dependency	old version	upgraded to
@grafana/data	next	^8.1.1
@grafana/toolkit	next	&8.1.1
@grafana/ui	next	^8.1.1
emotion	10.0.27	(no change)

I am not hell bent on any of these upgrades, as long as it continues to work.

NOTE I am questioning whether or not the grafana runtime should really be included here. It is not included in the grafana sample plugin. I think it should be a devDependency for compiling but that it should be provided by grafana at runtime. I'm mostly a backend datasource developer so I'm not certain of this - somebody who has more experience with these things please render an opinion via this ticket.

[acedrew]

@evannorton can you verify this builds and then get a signed release submitted?

[acedrew]

@wz2b See failing pipeline above, looks like it's all mostly the strict style guide, just running prettier with the grafana config should resolve everything