feat(indent): Implement basic indent for gdscript.

Indent is not handled correctly when adding new lines.
It seems that functions/loops/etc. are not recognized until they have at
least one indented block.

For example, if you enter a newline after `func foo():`, the cursor will
not be indented. If you manually indent and add a line like `pass`,
e.g.:

```
func foo():
    pass
```

now any insertions above or below `pass` will be indented correctly.
This might be an issue with the grammar, as it seems to apply to highlights
as well.

The following will not be highligted

```
func foo():
```

However, the following will be:

```
func foo():
    pass
```

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/indent/gdscript_spec.lua b/tests/indent/gdscript_spec.lua
new file mode 100644
index 000000000..c1770f41a
--- /dev/null
+++ b/tests/indent/gdscript_spec.lua
@@ -0,0 +1,20 @@
+local Runner = require("tests.indent.common").Runner
+
+local run = Runner:new(it, "tests/indent/gdscript", {
+  tabstop = 4,
+  shiftwidth = 4,
+  softtabstop = 0,
+  expandtab = false,
+})
+
+describe("indent GDScript:", function()
+  describe("whole file:", function()
+    run:whole_file(".", {
+      expected_failures = {},
+    })
+  end)
+
+  describe("new line:", function()
+    run:new_line("basic_blocks.gd", { on_line = 1, text = "var member := 0", indent = 0 })
+  end)
+end)