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/exclude/.dagger/env/default/.gitignore

@@ -0,0 +1,2 @@
+# dagger state
+state/**

tests/compute/exclude/.dagger/env/default/plan/main.cue

@@ -0,0 +1,41 @@
+package testing
+
+import (
+	"dagger.io/alpine"
+	"dagger.io/dagger"
+	"dagger.io/dagger/op"
+)
+
+TestData: dagger.#Artifact
+
+_expected: """
+	/src/b.txt
+	
+	/src/foo:
+	bar.txt
+	
+	"""
+
+TestIgnore: {
+	string
+	#up: [
+		op.#Load & {from: alpine.#Image},
+		op.#Exec & {
+			args: ["sh", "-c", "ls /src/* > /out.txt"]
+			mount: "/src": from: TestData
+		},
+		op.#Export & {source: "/out.txt"},
+		op.#Exec & {
+			args: [
+				"sh",
+				"-ec",
+				"""
+				cat > /test.txt << EOF
+				\(_expected)
+				EOF
+				test "$(cat /out.txt)" = "$(cat /test.txt)"
+				""",
+			]
+		},
+	]
+}

tests/compute/exclude/.dagger/env/default/values.yaml

@@ -0,0 +1,28 @@
+name: default
+inputs:
+    TestData:
+        dir:
+            path: ./testdata
+            exclude:
+                - a.txt
+                - '*/*.json'
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1gxwmtwahzwdmrskhf90ppwlnze30lgpm056kuesrxzeuyclrwvpsupwtpk
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSArcmRHMFByQkZSdGhteHhm
+            T2pSWW1UcU5LaFJabFJORllydFk3UkVsSHhVCndQZWNUKzVOeUovTTdCR3FmUXpO
+            c29GQXhpZkxwSmoweWxqZG1CMkcrRGcKLS0tIDhRMTVSc3NXSWIxSm55TGkwT1E1
+            L0NzY0RIMWNkc3k2WStOUGg4SndNRm8Kk7QSP/8spn1Set08VejVW9k4ZwBFqR0T
+            Ff/N73yNvo633hrfEJtTkhA/aZYyG9bPJy9s9vRDoNFkdTLSFcYX5g==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2021-05-28T23:20:28Z"
+    mac: ENC[AES256_GCM,data:nuRBGMu6MkiZ5DyuZy3drz4NXoUod8bYzOkJJiIj/fq2shN7oJNShF7UWDpW4FcknD5uldXpKqO3PmGpoxra95TTkoIHsbsQxSIrXUDhXl9CD5WOCwelUstv8f5r4nl+m3tSsW+4rIXdj/9ZB0DulMO0AqPp9I3XHG7glBMWYro=,iv:XGYGZpmC1dOIaTxcEJKtUmv1Fax+8ESPeWnjIGeOVPI=,tag:U/AKlJub9HsMrIpsjDxrYA==,type:str]
+    pgp: []
+    encrypted_suffix: secret
+    version: 3.7.1