Merge rows with matching cell and consecutive dates

here a simply way just use a group by function: copy this code in a blank query for you to see a example I did. 

let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjQyVtJRAqLcxLzE9NQiIMtQ31DfyAAsDmRAmLE6OJQaI5QaGmBRW1yapIBQbwQzT0fJGKY1NhYA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [employee = _t, number = _t, #"job title" = _t, date = _t, #"end date" = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"employee", Int64.Type}, {"number", type text}, {"job title", type text}, {"date", type date}, {"end date", type date}}),
#"Changed Type with Locale" = Table.TransformColumnTypes(#"Changed Type", {{"date", type date}}, "en-US"),
#"Changed Type with Locale1" = Table.TransformColumnTypes(#"Changed Type with Locale", {{"end date", type date}}, "en-US"),
#"Grouped Rows" = Table.Group(#"Changed Type with Locale1", {"employee", "job title"}, {{"Date", each List.Min([date]), type nullable date}, {"End date", each List.Max([end date]), type nullable date}})
in
#"Grouped Rows"