Feature: Add Surface language and integrate with Elixir (#1645)

* Add initial surface highlights & injections

* Additional surface highlights

* Filetype detection, fix injections

* Fix Elixir function highlight when left is an identifier

* Add surface parser

* Fix comment highlights

* Surface folds, indents, better highlights

* Highlight surface components & directives

* Restore comments Elixir injections

queries/surface/folds.scm

@@ -0,0 +1,5 @@
+; Surface folds similar to HTML and includes blocks
+[
+  (tag)
+  (block)
+] @fold

queries/surface/highlights.scm

@@ -0,0 +1,46 @@
+; Surface text is highlighted as such
+(text) @text
+
+; Surface has two types of comments, both are highlighted as such
+(comment) @comment
+
+; Surface attributes are highlighted as HTML attributes
+(attribute_name) @tag.attribute
+
+; Attributes are highlighted as strings
+(attribute_value) @string
+
+; Surface blocks are highlighted as keywords
+[
+  (start_block) 
+  (end_block)
+  (subblock)
+] @keyword
+
+; Surface supports HTML tags and are highlighted as such
+[
+  (start_tag)
+  (end_tag)
+  (self_closing_tag)
+  (start_component)
+  (end_component)
+  (self_closing_component)
+] @tag.delimiter
+
+; Expressions are similar to string interpolation, and are highloghted as such
+(expression) @punctuation.special
+
+; Expressions should be highlighted as Elixir, fallback to special strings
+(expression_value) @string.special
+
+; Surface tags are highlighted as HTML
+(tag_name) @tag
+
+; Surface components are highlighted as types (Elixir modules)
+(component_name) @type
+
+; Surface directives are highlighted as keywords
+(directive_name) @keyword
+
+; Surface operators
+["="] @operator

queries/surface/indents.scm

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+; Surface indents like HTML, with the addition of blocks 
+[
+  (tag)
+  (block)
+] @indent
+
+; Dedent at the end of each tag, as well as a subblock
+[
+  (end_tag)
+  (end_block)
+  (subblock)
+] @branch

queries/surface/injections.scm

@@ -0,0 +1,8 @@
+; Surface expressions and components are Elixir code
+[
+  (expression_value)
+  (component_name)
+] @elixir
+
+; Surface comments are nvim-treesitter comments
+(comment) @comment