Add --pre flag to pip installs for using nightly versions. (#19145)

Progress on #18938.

Pip will only install "pre-release" versions if `--pre` is set or the
version is set explicitly:
https://pip.pypa.io/en/stable/cli/pip_install/#pre-release-versions. The
`rc` part of our `rcYYYYMMDD` suffix used in the nightly packages is
considered a "Pre-release segment" in the version string:
https://packaging.python.org/en/latest/specifications/version-specifiers/#public-version-identifiers.

Also switched sample Colab notebooks to use the new package names. I
tested these lightly, but did not fully regenerate them, so the embedded
logs still reference old versions of packages:
* Manually ran a few notebooks from my branch like
https://colab.research.google.com/github/ScottTodd/iree/blob/release-pre/samples/colab/tensorflow_edge_detection.ipynb
* Ran the 'samples' workflow on my fork:
https://github.com/ScottTodd/iree/actions/runs/11828250281

Author: ScottTodd

.github/workflows/samples.yml

@@ -86,6 +86,7 @@ jobs:
           python3 -m pip install \
             --find-links https://iree.dev/pip-release-links.html \
             --upgrade \
+            --pre \
             iree-base-compiler \
             iree-base-runtime
       - name: "Setup emsdk"

docs/website/docs/developers/debugging/integration-tests.md

@@ -71,9 +71,9 @@ All steps here assume starting from the IREE root directory.
     Install distributed packages
 
     ```bash
-    # Install packages from nightly releases
+    # Install packages from nightly pre-releases
     # This should work for most cases, as the importers change infrequently
-    python -m pip install \
+    python -m pip install --pre \
       iree-base-compiler iree-base-runtime iree-tools-tf iree-tools-tflite \
       --find-links https://iree.dev/pip-release-links.html
     ```

docs/website/docs/guides/deployment-configurations/snippets/_iree-compiler-from-release.md

@@ -9,13 +9,13 @@
 
 === ":material-alert: Nightly releases"
 
-    Nightly releases are published on
+    Nightly pre-releases are published on
     [GitHub releases](https://github.com/iree-org/iree/releases).
 
     ``` shell
     python -m pip install \
       --find-links https://iree.dev/pip-release-links.html \
-      --upgrade iree-base-compiler
+      --upgrade --pre iree-base-compiler
     ```
 
 !!! tip

docs/website/docs/guides/deployment-configurations/snippets/_iree-runtime-from-release.md

@@ -9,11 +9,11 @@
 
 === ":material-alert: Nightly releases"
 
-    Nightly releases are published on
+    Nightly pre-releases are published on
     [GitHub releases](https://github.com/iree-org/iree/releases).
 
     ``` shell
     python -m pip install \
       --find-links https://iree.dev/pip-release-links.html \
-      --upgrade iree-base-runtime
+      --upgrade --pre iree-base-runtime
     ```

docs/website/docs/guides/ml-frameworks/onnx.md

@@ -70,13 +70,14 @@ graph LR
 
     === ":material-alert: Nightly releases"
 
-        Nightly releases are published on
+        Nightly pre-releases are published on
         [GitHub releases](https://github.com/iree-org/iree/releases).
 
         ``` shell
         python -m pip install \
           --find-links https://iree.dev/pip-release-links.html \
           --upgrade \
+          --pre \
           iree-base-compiler[onnx] \
           iree-base-runtime
         ```

docs/website/docs/guides/ml-frameworks/tensorflow.md

@@ -80,6 +80,7 @@ graph LR
         python -m pip install \
           --find-links https://iree.dev/pip-release-links.html \
           --upgrade \
+          --pre \
           iree-base-compiler \
           iree-base-runtime \
           iree-tools-tf

docs/website/docs/guides/ml-frameworks/tflite.md

@@ -75,6 +75,7 @@ graph LR
         python -m pip install \
           --find-links https://iree.dev/pip-release-links.html \
           --upgrade \
+          --pre \
           iree-base-compiler \
           iree-base-runtime \
           iree-tools-tflite

docs/website/docs/reference/bindings/python.md

@@ -83,15 +83,16 @@ To use IREE's Python bindings, you will first need to install
       iree-base-runtime
     ```
 
-=== ":material-alert: Nightly releases"
+=== ":material-alert: Nightly pre-releases"
 
-    Nightly releases are published on
+    Nightly pre-releases are published on
     [GitHub releases](https://github.com/iree-org/iree/releases).
 
     ``` shell
     python -m pip install \
       --find-links https://iree.dev/pip-release-links.html \
       --upgrade \
+      --pre \
       iree-base-compiler \
       iree-base-runtime
     ```

experimental/web/generate_web_metrics.sh

@@ -65,7 +65,7 @@ trap "deactivate 2> /dev/null" EXIT
 # Skip package installs when you want by commenting this out. Freezing to a
 # specific version when iterating on metrics is useful, and fetching is slow.
 
-python -m pip install --upgrade \
+python -m pip install --upgrade --pre \
   --find-links https://iree.dev/pip-release-links.html \
   iree-base-compiler iree-tools-tflite
 

samples/colab/low_level_invoke_function.ipynb

@@ -66,7 +66,7 @@
         "outputId": "0339165a-a35f-4b46-9cf8-f22adc69a7fe"
       },
       "source": [
-        "!python -m pip install iree-compiler iree-runtime -f https://iree.dev/pip-release-links.html"
+        "!python -m pip install --pre iree-base-compiler iree-base-runtime -f https://iree.dev/pip-release-links.html"
       ],
       "execution_count": 2,
       "outputs": [