Python: Bottle Framework Header Support

[Kwstubbs]

Add Bottle Header support

[RasmusWL]

Thanks 🎉

Overall the code looks OK to me, but to accept this PR I need you to write some tests 😊 (good start by copying over the ConceptsTest, but we also need some code using bottle to show that the modeling works as intended) See flask tests as an inspiration.

[RasmusWL]

This code looks like it will work for both reads and writes to bottle.response.headers?

might want to just do the same as we do for flask/werkzeug:

codeql/python/ql/lib/semmle/python/frameworks/Werkzeug.qll

Lines 216 to 239 in d4a0728

	/** A dict-like write to a header, assumed to be a response header. */
	private class HeaderWriteSubscript extends Http::Server::ResponseHeaderWrite::Range,
	DataFlow::Node
	{
	DataFlow::Node name;
	DataFlow::Node value;
	HeaderWriteSubscript() {
	exists(SubscriptNode subscript |
	this.asCfgNode() = subscript and
	value.asCfgNode() = subscript.(DefinitionNode).getValue() and
	name.asCfgNode() = subscript.getIndex() and
	subscript.getObject() = instance().asCfgNode()
	)
	}
	override DataFlow::Node getNameArg() { result = name }
	override DataFlow::Node getValueArg() { result = value }
	override predicate nameAllowsNewline() { any() }
	override predicate valueAllowsNewline() { none() }
	}