[Flakes] Changes to local flakes should reflect in shell after devbox install (#1063)

## Summary

**Problem:** Changes to local flakes would not be reflected in the
current shell.

**Product workflow after this fix:**
1. User should edit the flake.nix file.
2. User should run `devbox install`.
3. The newly updated binaries from the flake should be available in
their environment.

This PR makes two fixes:
1. Changes the `devbox.ConfigHash` to incorporate the contents of local
flake files i.e. local inputs.
2. Calls `wrapnix.CreateWrappers` in `devbox.PrintEnv` to ensure that we
re-create the binary wrappers
   to point to the latest binaries installed by the local flake. 

## How was it tested?

the below was run within `devbox shell` of each example.

in `examples/flakes/php/my-php-flake/flake.nix`, removed `ds` extension.
Ran `devbox install`. And confirmed `ds` was removed via getting no
output from `php -m | grep ds`.
I then re-added `ds` extension back, re-ran `devbox install` and this
time `php -m | grep ds` returned a result.

in `examples/flakes/go-mod/ory-cli`, I changed the post-install binary's
name from `ory` to `ory-renamed`. Ran `devbox install` and `which
ory-renamed` returned a path to the binary.

Author: savil

internal/impl/devbox.go

@@ -110,7 +110,12 @@ func (d *Devbox) Config() *devconfig.Config {
 }
 
 func (d *Devbox) ConfigHash() (string, error) {
-	return d.cfg.Hash()
+	hashes := lo.Map(d.packagesAsInputs(), func(i *nix.Input, _ int) string { return i.Hash() })
+	h, err := d.cfg.Hash()
+	if err != nil {
+		return "", err
+	}
+	return cuecfg.Hash(h + strings.Join(hashes, ""))
 }
 
 func (d *Devbox) NixPkgsCommitHash() string {
@@ -280,6 +285,10 @@ func (d *Devbox) PrintEnv(ctx context.Context, includeHooks bool) (string, error
 		return "", err
 	}
 
+	if err := wrapnix.CreateWrappers(ctx, d); err != nil {
+		return "", err
+	}
+
 	envStr := exportify(envs)
 
 	if includeHooks {

internal/nix/input.go

@@ -64,7 +64,7 @@ var inputNameRegex = regexp.MustCompile("[^a-zA-Z0-9-]+")
 func (i *Input) InputName() string {
 	result := ""
 	if i.IsLocal() {
-		result = filepath.Base(i.Path) + "-" + i.hash()
+		result = filepath.Base(i.Path) + "-" + i.Hash()
 	} else if i.IsGithub() {
 		result = "gh-" + strings.Join(strings.Split(i.Opaque, "/"), "-")
 	} else if url := i.URLForInput(); IsGithubNixpkgsURL(url) {
@@ -74,7 +74,7 @@ func (i *Input) InputName() string {
 		}
 		result = "nixpkgs-" + u
 	} else {
-		result = i.String() + "-" + i.hash()
+		result = i.String() + "-" + i.Hash()
 	}
 	return inputNameRegex.ReplaceAllString(result, "-")
 }
@@ -221,7 +221,7 @@ func (i *Input) urlWithoutFragment() string {
 	return u.String()
 }
 
-func (i *Input) hash() string {
+func (i *Input) Hash() string {
 	// For local flakes, use content hash of the flake.nix file to ensure
 	// user always gets newest input.
 	if i.IsLocal() {