Add .lkml to LookML (#3454)

* Add .lkml to LookML

* Limit .lkml to .view.lkml and .model.lkml

* Add lkml samples

* Fix extension order

samples/LookML/example.model.lkml

@@ -0,0 +1,49 @@
+- label:          'desired label name'
+- connection:     connection_name
+- include:        filename_or_pattern
+  # Possibly more include declarations
+- persist_for:    N (seconds | minutes | hours)
+- case_sensitive: true | false
+- week_start_day: monday | tuesday | wednesday | thursday | friday | saturday | sunday
+- value_formats:
+  - name: desired_format_name
+    value_format: 'excel-style formatting string'
+  # Possibly more value formats
+
+- explore: view_name
+  label:  'desired label name'
+  description: 'description string'
+  symmetric_aggregates: true | false
+  hidden: true | false
+  fields: [field_or_set, field_or_set, …]
+
+  sql_always_where: SQL WHERE condition
+  always_filter:
+    field_name: 'looker filter expression'
+  conditionally_filter:
+    field_name: 'looker filter expression'
+    unless: [field_or_set, field_or_set, …]
+  access_filter_fields: [fully_scoped_field, fully_scoped_field, …]
+
+  always_join: [view_name, view_name, …]
+  joins:
+    - join: view_name
+      type: left_outer | full_outer | inner | cross
+      relationship: one_to_one | many_to_one | one_to_many | many_to_many
+      from: view_name
+      sql_table_name: table_name
+      view_label: 'desired label name'
+      fields: [field_or_set, field_or_set, …]
+      required_joins: [view_name, view_name, …]
+      foreign_key: dimension_name
+      sql_on: SQL ON clause
+    # Possibly more join declarations
+
+  persist_for: N (seconds | minutes | hours)
+  from: view_name
+  view: view_name
+  case_sensitive: true | false
+  sql_table_name: table_name
+  cancel_grouping_fields: [fully_scoped_field, fully_scoped_field, …]
+
+# Possibly more explore declarations

samples/LookML/example.view.lkml

@@ -0,0 +1,90 @@
+- view: view_name
+  sql_table_name: table_name
+  suggestions: true | false
+
+  derived_table:
+    sql: SQL query
+    persist_for: N (seconds | minutes | hours)
+    sql_trigger_value: SQL query
+    distribution: column_name
+    distribution_style: ALL | EVEN
+    sortkeys: [column_name, column_name, …]
+    indexes: [column_name, column_name, …]
+
+  sets:
+    set_name:
+      - field_or_set
+      - field_or_set
+      - …
+    # Possibly more set declarations
+
+  fields:
+  - (dimension | dimension_group | measure | filter): field_name
+    label: 'desired label name'
+    view_label: 'desired label name'
+    group_label: 'desired label name'
+    description: 'description string'
+    hidden: true | false
+    alias: [old_field_name, old_field_name, …]
+    value_format: 'excel-style formatting string'
+    value_format_name: format_name
+    html: HTML expression using Liquid template elements
+    sql: SQL expression to generate the field value
+    required_fields: [field_name, field_name, …]
+    drill_fields: [field_or_set, field_or_set, …]
+    can_filter: true | false
+    fanout_on: repeated_record_name
+
+    # DIMENSION SPECIFIC PARAMETERS
+
+    type: dimension_field_type
+    primary_key: true | false
+    sql_case:
+      value: SQL condition
+      value: SQL condition
+      # Possibly more sql_case statements
+    alpha_sort: true | false
+    tiers: [N, N, …]
+    style: classic | interval | integer | relational
+    sql_latitude: SQL expression to generate a latitude
+    sql_longitude: SQL expression to generate a longitude
+    suggestable: true | false
+    suggest_persist_for: N (seconds | minutes | hours)
+    suggest_dimension: dimension_name
+    suggest_explore: explore_name
+    suggestions: ['suggestion string', 'suggestion string', …]
+    bypass_suggest_restrictions: true | false
+    full_suggestions: true | false
+    skip_drill_filter: true | false
+    case_sensitive: true | false
+    order_by_field: dimension_name
+    map_layer: name_of_map_layer
+    links:
+      - label: 'desired label name'
+        url: desired_url
+        icon_url: url_of_an_ico_file
+      # Possibly more links
+
+    # DIMENSION GROUP SPECIFIC PARAMETERS
+
+    timeframes: [timeframe, timeframe, …]
+    convert_tz: true | false
+    datatype: epoch | timestamp | datetime | date | yyyymmdd
+
+    # MEASURE SPECIFIC PARAMETERS
+
+    type: measure_field_type
+    direction: row | column
+    approximate: true | false
+    approximate_threshold: N
+    sql_distinct_key: SQL expression to define repeated entities
+    list_field: dimension_name
+    filters:
+      dimension_name: 'looker filter expression'
+      # Possibly more filters statements
+
+    # FILTER SPECIFIC PARAMETERS
+
+    default_value: 'desired default value'
+
+  # Possibly more dimension or measure declarations