add support for excludes in input dir

This adds support for `--include` and `--exclude` for directory inputs.

For instance, this is what you would want to use when passing dagger
repository as an input:

```
inputs:
    repository:
        dir:
            path: .
            exclude:
                - '**/node_modules'
                - cmd/dagger/dagger
                - cmd/dagger/dagger-debug
```

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

tests/compute.bats

@@ -94,6 +94,6 @@ setup() {
     assert_output "secret=mySecret"
 }
 
-@test ".daggerignore" {
-    "$DAGGER" compute --input-dir TestData="$TESTDIR"/compute/ignore/testdata "$TESTDIR"/compute/ignore
+@test "compute: exclude" {
+    "$DAGGER" up -w "$TESTDIR"/compute/exclude
 }