Move install-related dev scripts to device/ folder (#1793)

Related #1716. Stacked on
#1791.

This PR moves both install-related dev scripts to a new subfolder
`device/`. This is mostly for clarity, to communicate that these two
scripts are not supposed to be executed on a dev machine.

Initially I thought we should also move the [`enable-passwordless-sudo`
script](https://github.com/tiny-pilot/tinypilot/blob/master/dev-scripts/enable-passwordless-sudo)
there as well, but I’m not so sure about that anymore, because I think
it also would be possible to run it in a dev environment. E.g., we also
[run it on CI for the e2e
tests](https://github.com/tiny-pilot/tinypilot/blob/3323b235e53d2306c5daba58a1d855d5d1575d91/.circleci/config.yml#L162-L164).
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---------

Co-authored-by: Jan Heuermann <[email protected]>

CONTRIBUTING.md

@@ -163,9 +163,9 @@ To build and install your changes on device, perform the following steps:
    ```
 1. On the device, clone the TinyPilot repo to a temporary directory.
 1. Check out the branch that has your changes.
-1. Run the [`dev-scripts/install-from-source`](dev-scripts/install-from-source) script to build and install your branch's code. For example:
+1. Run the [`dev-scripts/device/install-from-source`](dev-scripts/device/install-from-source) script to build and install your branch's code. For example:
    ```bash
-   sudo dev-scripts/install-from-source
+   sudo dev-scripts/device/install-from-source
    ```
 
 ### Installing a TinyPilot bundle
@@ -188,7 +188,7 @@ curl \
   --silent \
   --show-error \
   --location \
-  https://raw.githubusercontent.com/tiny-pilot/tinypilot/master/dev-scripts/install-bundle | \
+  https://raw.githubusercontent.com/tiny-pilot/tinypilot/master/dev-scripts/device/install-bundle | \
   sudo bash -s -- \
     url-to-bundle-file # replace this line with your bundle URL
 ```

dev-scripts/install-from-source → dev-scripts/device/install-from-source

@@ -45,4 +45,4 @@ mv "${LATEST_DEBIAN_PACKAGE}" ./bundler/bundle/
 LATEST_INSTALL_BUNDLE="${PWD}/$(ls -t bundler/dist/tinypilot*.tgz | head -n 1)"
 readonly LATEST_INSTALL_BUNDLE
 
-sudo ./dev-scripts/install-bundle "${LATEST_INSTALL_BUNDLE}"
+sudo ./dev-scripts/device/install-bundle "${LATEST_INSTALL_BUNDLE}"