use new github issue forms for build-failure and sandbox-limits templates

.github/ISSUE_TEMPLATE/crate-build-failure.yaml

@@ -0,0 +1,22 @@
+---
+name: Crate Build Failure
+description: My crate failed to build in docs.rs.
+labels: build-failure
+body:
+  - type: markdown
+    attributes:
+      value: |
+        If you need a system dependency added for your crate to build, consider making a PR to [rust-lang/crates-build-env](https://github.com/rust-lang/crates-build-env) instead of opening an issue here. There are detailed instructions for this [on this page](https://forge.rust-lang.org/docs-rs/add-dependencies.html).
+  - type: input
+    attributes:
+      label: Crate name
+    validations:
+      required: true
+  - type: input
+    attributes:
+      label: Build failure link
+    validations:
+      required: true
+  - type: textarea
+    attributes:
+      label: Additional details

.github/ISSUE_TEMPLATE/sandbox-limits-increase-request.yaml

@@ -0,0 +1,36 @@
+---
+name: Sandbox Limits Increase Request
+description: My crate build won't complete within the sandbox limits.
+labels: limits-increase
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Please note we *won't* enable network access or allow the crate to write in read-only directories, to avoid compromising the security of docs.rs itself.
+  - type: input
+    attributes:
+      label: Crate name
+    validations:
+      required: true
+  - type: input
+    attributes:
+      label: Build failure link
+    validations:
+      required: true
+  - type: input
+    attributes:
+      label: Requested RAM limit
+      placeholder: "default: 3 GB"
+  - type: input
+    attributes:
+      label: Requested timeout
+      placeholder: "default: 15 minutes"
+  - type: input
+    attributes:
+      label: Requested number of targets
+      placeholder: "default: 10"
+  - type: textarea
+    attributes:
+      label: Why your crate needs the resource increases
+    validations:
+      required: true