[management, infrastructure, idp] Simplified IdP Management - Embedded IdP (#5008)

Embed Dex as a built-in IdP to simplify self-hosting setup.
Adds an embedded OIDC Identity Provider (Dex) with local user management and optional external IdP connectors (Google/GitHub/OIDC/SAML), plus device-auth flow for CLI login. Introduces instance onboarding/setup endpoints (including owner creation), field-level encryption for sensitive user data, a streamlined self-hosting provisioning script, and expanded APIs + test coverage for IdP management.

more at https://github.com/netbirdio/netbird/pull/5008#issuecomment-3718987393

idp/dex/web/templates/password.html

@@ -0,0 +1,58 @@
+{{ template "header.html" . }}
+
+<div class="nb-card">
+    <h1 class="nb-heading">Sign in</h1>
+    <p class="nb-subheading">Enter your credentials</p>
+
+    <form method="post" action="{{ .PostURL }}">
+        {{ if .Invalid }}
+        <div class="nb-error">
+            Invalid {{ .UsernamePrompt }} or password.
+        </div>
+        {{ end }}
+
+        <div class="nb-form-group">
+            <label class="nb-label" for="login">{{ .UsernamePrompt }}</label>
+            <input
+                type="text"
+                id="login"
+                name="login"
+                class="nb-input"
+                placeholder="Enter your {{ .UsernamePrompt | lower }}"
+                {{ if .Username }}value="{{ .Username }}"{{ else }}autofocus{{ end }}
+                required
+            >
+        </div>
+
+        <div class="nb-form-group">
+            <label class="nb-label" for="password">Password</label>
+            <input
+                type="password"
+                id="password"
+                name="password"
+                class="nb-input"
+                placeholder="Enter your password"
+                {{ if .Invalid }}autofocus{{ end }}
+                required
+            >
+        </div>
+
+        <button type="submit" id="submit-login" class="nb-btn">
+            Sign in
+        </button>
+    </form>
+
+    {{ if .BackLink }}
+    <div class="nb-back-link">
+        <a href="{{ .BackLink }}" class="nb-link">Choose another login method</a>
+    </div>
+    {{ end }}
+</div>
+
+<script>
+document.querySelector('form').onsubmit = function() {
+    document.getElementById('submit-login').disabled = true;
+};
+</script>
+
+{{ template "footer.html" . }}