`--file` treats query params in HTTP URLs as path assignments

**What steps did you take:**

ytt the bootstrapper resources I am given by Tanzu Platform in form of a HTTP URL which contains query params

**What happened:**

```shell
ytt -f "https://example.com/?id=123&source=hello"
```

```
ytt: Error: Expected file 'https://example.com/?id=123&source=hello' to only have single '=' sign to for relative path assignment
```

**What did you expect:**

ytt fetches the file and templates it.

**Anything else you would like to add:**

I can workaround the issue with, say

```shell
http "https://example.com/?id=123&source=hello" | ytt -f-
```

**Environment:**

- ytt version (use `ytt --version`): `0.50.0`
- OS (e.g. from `/etc/os-release`): `macOS`

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Reproduce the reported `ytt -f "https://example.com/?id=123&source=hello"` command and trace the CLI's `--file` argument parsing and HTTP URL handling. Done means a URL containing query parameters is fetched and templated rather than treated as a relative path assignment; compare with the documented `ytt -f-` workaround.

Written by the indexing model from the issue text.