Closes #11558: Add support for remote data sources (#11646)

* WIP

* WIP

* Add git sync

* Fix file hashing

* Add last_synced to DataSource

* Build out UI & API resources

* Add status field to DataSource

* Add UI control to sync data source

* Add API endpoint to sync data sources

* Fix display of DataSource job results

* DataSource password should be write-only

* General cleanup

* Add data file UI view

* Punt on HTTP, FTP support for now

* Add DataSource URL validation

* Add HTTP proxy support to git fetcher

* Add management command to sync data sources

* DataFile REST API endpoints should be read-only

* Refactor fetch methods into backend classes

* Replace auth & git branch fields with general-purpose parameters

* Fix last_synced time

* Render discrete form fields for backend parameters

* Enable dynamic edit form for DataSource

* Register DataBackend classes in application registry

* Add search indexers for DataSource, DataFile

* Add single & bulk delete views for DataFile

* Add model documentation

* Convert DataSource to a primary model

* Introduce pre_sync & post_sync signals

* Clean up migrations

* Rename url to source_url

* Clean up filtersets

* Add API & filterset tests

* Add view tests

* Add initSelect() to HTMX refresh handler

* Render DataSourceForm fieldsets dynamically

* Update compiled static resources

docs/models/core/datafile.md

@@ -0,0 +1,25 @@
+# Data Files
+
+A data file object is the representation in NetBox's database of some file belonging to a remote [data source](./datasource.md). Data files are synchronized automatically, and cannot be modified locally (although they can be deleted).
+
+## Fields
+
+### Source
+
+The [data source](./datasource.md) to which this file belongs.
+
+### Path
+
+The path to the file, relative to its source's URL. For example, a file at `/opt/config-data/routing/bgp/peer.yaml` with a source URL of `file:///opt/config-data/` would have its path set to `routing/bgp/peer.yaml`.
+
+### Last Updated
+
+The date and time at which the file most recently updated from its source. Note that this attribute is updated only when the file's contents have been modified. Re-synchronizing the data source will not update this timestamp if the upstream file's data has not changed.
+
+### Size
+
+The file's size, in bytes.
+
+### Hash
+
+A [SHA256 hash](https://en.wikipedia.org/wiki/SHA-2) of the file's data. This can be compared to a hash taken from the original file to determine whether any changes have been made.

docs/models/core/datasource.md

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+# Data Sources
+
+A data source represents some external repository of data which NetBox can consume, such as a git repository. Files within the data source are synchronized to NetBox by saving them in the database as [data file](./datafile.md) objects.
+
+## Fields
+
+### Name
+
+The data source's human-friendly name.
+
+### Type
+
+The type of data source. Supported options include:
+
+* Local directory
+* git repository
+
+### URL
+
+The URL identifying the remote source. Some examples are included below.
+
+| Type | Example URL |
+|------|-------------|
+| Local | file:///var/my/data/source/ |
+| git | https://https://github.com/my-organization/my-repo |
+
+### Status
+
+The source's current synchronization status. Note that this cannot be set manually: It is updated automatically when the source is synchronized.
+
+### Enabled
+
+If false, synchronization will be disabled.
+
+### Ignore Rules
+
+A set of rules (one per line) identifying filenames to ignore during synchronization. Some examples are provided below. See Python's [`fnmatch()` documentation](https://docs.python.org/3/library/fnmatch.html) for a complete reference.
+
+| Rule           | Description                              |
+|----------------|------------------------------------------|
+| `README`       | Ignore any files named `README`          |
+| `*.txt`        | Ignore any files with a `.txt` extension |
+| `data???.json` | Ignore e.g. `data123.json`               |
+
+### Last Synced
+
+The date and time at which the source was most recently synchronized successfully.