Breaking change: Field types in `codersdk.UpdateTemplateMeta` for
`Icon`, `Description`, and `DisplayName` moved to `*string`
## Summary
In this pull request we're updating the `UpdateTemplateMeta` struct to
allow `DisplayName`, `Description`, and `Icon` to be set as empty `""`
or default to the value from the template if not provided in an update
call.
Fixes https://github.com/coder/coder/issues/19036
### The bug
The reported bug occurred when clients were attempting to update a
metadata field in a template via an edit call. When the request was
decoded into an `UpdateTemplateMeta` struct the default values for
fields in the struct were used to update the template even if they
weren't provided. This led to fields like `Icon` being set to `""` (the
default value).
### Changes
To allow for specific fields to be set to `""` these fields were updated
to be `*string` as opposed to `string`. This allows for clients to set
these fields as `""` in an update request or they will default to the
template value if they are not provided in the update request (will be
`nil`).
Added tests to confirm empty and nil values and updated other tests that
use these fields.
Rafael Rodriguez
aab2ccdb38