Add Microsoft Ad Extensions

Adds SITELINK, CALLOUT and/or STRUCTURED SNIPPET ad extensions to a Microsoft (Bing) campaign: the extra links and highlights that make the ad taller and lift CTR. sitelinks: lines in 'Display text|https://url' or 'text|url|description1|description2' format (display text ≤25 chars with descriptions, ≤35 without; descriptions ≤35 chars and given together); a '|' inside a text is written as '\|'. callouts: short highlight phrases (≤25 chars each). structured_snippets: lines in 'Header|value1, value2, value3' format, 3 to 10 values of ≤25 chars; the header must be one of Microsoft's fixed headers written in the ad language (English: Services, Brands, Types; German: Dienstleistungen, Marken, Typen; Spanish: Servicios, Marcas; French: Services, Marques; Turkish: Hizmetler, Markalar). An editorial rejection names the rejected word and Microsoft's reason code, so that word can be rephrased. To change an existing sitelink use update_microsoft_sitelink. Creates them in the account library and attaches them to the campaign in one call. confirm=false = preview, confirm=true applies.