✨ Add Linear Trigger node (#2767)

* ✨ Linear Trigger

* 🎨 Replace PNG with SVG icon

Co-authored-by: Iván Ovejero <ivov.src@gmail.com>

packages/nodes-base/nodes/Linear/GenericFunctions.ts

@@ -0,0 +1,45 @@
+import {
+	OptionsWithUri,
+} from 'request';
+
+import {
+	IExecuteFunctions,
+	ILoadOptionsFunctions,
+} from 'n8n-core';
+
+import {
+	IDataObject,
+	IHookFunctions,
+	IWebhookFunctions,
+	NodeApiError,
+	NodeOperationError,
+} from 'n8n-workflow';
+
+export async function linearApiRequest(this: IExecuteFunctions | IWebhookFunctions | IHookFunctions | ILoadOptionsFunctions, body: any = {}, option: IDataObject = {}): Promise<any> { // tslint:disable-line:no-any
+	const credentials = await this.getCredentials('linearApi') as IDataObject;
+
+	const endpoint = 'https://api.linear.app/graphql';
+
+	let options: OptionsWithUri = {
+		headers: {
+			'Content-Type': 'application/json',
+			Authorization: credentials.apiKey,
+		},
+		method: 'POST',
+		body,
+		uri: endpoint,
+		json: true,
+	};
+	options = Object.assign({}, options, option);
+	try {
+
+		return await this.helpers.request!(options);
+
+	} catch (error) {
+		throw new NodeApiError(this.getNode(), error);
+	}
+}
+
+export function capitalizeFirstLetter(data: string) {
+	return data.charAt(0).toUpperCase() + data.slice(1);
+}