Added USD as a language + some queries

Added USD highlight unittests

Added USD indentation

Added USD indents.scm file

Added USD indent rules

Simplified USD highlight groups

Added explicit highlight groups

Added newline

Removed after/ftdetect/usda.lua

usd/indents.scm - Added inline comments explaining the nodes

Fixed USD highlight group unittests

Added indentation unittests

Simplified USD `@identifier` highlighting

Added USD documentation highlight group tests

Simplified USD highlight groups

Moved USD `@identifier` and `@namespace` highlights into one place

Removed and simplified tests/query/highlights/usd

Simplified tests/query/highlights/usd more

Removed trailing newline

Combined USD test files

Added `set filetype=usd` to minimal_init.lua

tests/indent/usd/prim.usd

@@ -0,0 +1,6 @@
+#usda 1.0
+
+def "foo" (
+)
+{
+}

tests/indent/usd_spec.lua

@@ -0,0 +1,21 @@
+local Runner = require("tests.indent.common").Runner
+
+local run = Runner:new(it, "tests/indent/usd", {
+  tabstop = 4,
+  shiftwidth = 4,
+  softtabstop = 4,
+  expandtab = true,
+})
+
+describe("indent USD:", function()
+  describe("whole file:", function()
+    run:whole_file(".", {
+      expected_failures = {},
+    })
+  end)
+
+  describe("new line:", function()
+    run:new_line("prim.usd", { on_line = 3, text = "active = false", indent = 4 })
+    run:new_line("prim.usd", { on_line = 5, text = "custom int foo = 10", indent = 4 })
+  end)
+end)

tests/query/highlights/usd/prims.usda

@@ -0,0 +1,118 @@
+def Xform "cube" (
+    assetInfo = {
+    # <- keyword
+        asset[] payloadAssetDependencies = [@fizz.usd@, @buzz.usd@]
+        # <- type
+        #       ^ keyword
+        #                                   ^ text.uri
+        #                                               ^ text.uri
+    }
+)
+{
+}
+
+def "root" (
+    add references = @foo.usda@</Model> (offset = 1; scale = 2.0)
+                      # <- text.uri
+                      #        ^ string.special
+                      #                  ^ keyword
+                      #                           ^ number
+                      #                            ^ punctuation.delimiter
+                      #                              ^ keyword
+                      #                                      ^ float
+)
+{
+}
+
+def "World"
+{
+    over "points" (
+        clips = {
+        # <- keyword
+            dictionary default = {
+            # <- type
+            #          ^ variable
+                double2[] times = [(101, 101), (102, 102)]
+                # <- type
+                #         ^ keyword
+                #                   ^ number
+            }
+        }
+    )
+    {
+    }
+}
+
+def Xform "torch_2" (
+    payload = @./torch.usda@
+    kind = "model"
+)
+{
+    // Pre-published light list
+    # <- comment
+    rel lightList = [ <light> ]  # inline comment
+    #                            ^ comment
+    token lightList:cacheBehavior = "consumeAndContinue"
+
+    double3 xformOp:translate = (1, 0, 0.5)
+    uniform token[] xformOpOrder = ["xformOp:translate"]
+}
+
+def "foo" (
+  "some comment"
+  # <- comment.documentation
+)
+{
+}
+
+def "foo" (
+  # inline comment
+  "actual in-description comment"
+  # <- comment.documentation
+)
+{
+}
+
+def "foo" (
+    add references = @foo.usda@
+    # <- function.call
+    append references = @foo.usda@
+    # <- function.call
+    delete references = @foo.usda@
+    # <- function.call
+    reorder references = [@foo.usda@]
+    # <- function.call
+
+    references = [@foo.usda@]  # explicit
+)
+{
+}
+
+over "Parent" (
+    prepend references = [</InternalRef>, @./ref.usda@</RefParent>]
+    # <- function.call
+    #       ^ keyword
+    #                     ^ string.special
+    #                                     ^ text.uri
+    #                                                 ^ string.special
+)
+{
+}
+
+def "foo"
+{
+    float value.timeSamples = {
+    # <- type
+    #     ^ variable
+    #           ^ property
+      -414: 14.4
+      # <- number
+      #     ^ float
+      10: 201.0,
+      # <- number
+      #   ^ float
+      10.123: 201.0123,
+      # <- float
+      #       ^ float
+    }
+}

tests/query/highlights/usd/properties.usda

@@ -0,0 +1,21 @@
+dictionary foo = {}
+# <- type
+half[] foo = [2, 1, 2]
+# <- type
+string foo = "something"
+# <- type
+timecode time = 1.0
+# <- type
+token[] purpose = ["default", "render"]
+# <- type
+
+rel material:binding:collection:Erasers = None
+# <- type
+#   ^ namespace
+#           ^ punctuation.delimiter
+#            ^ namespace
+#                   ^ punctuation.delimiter
+#                    ^ namespace
+#                              ^ punctuation.delimiter
+#                               ^ variable
+#                                         ^ constant.builtin

tests/query/highlights/usd/subLayers.usda

@@ -0,0 +1,9 @@
+#usda 1.0
+(
+    subLayers = [
+    # <- keyword
+        @./model_sub.usda@ (offset = 1)
+        # <- text.uri
+        #                   ^ keyword
+    ]
+)