[feature] Add /api/v1/admin/custom_emojis endpoint (#902)

* add admin emojis get path + model + docs

* stub admin emojis get processor function

* add id + disabled fields to admin emoji

* add emoji -> api admin emoji converter

* tidy up a bit

* add GetEmojis function

* finish up get emojis function

* order by shortcodedomain

* ASC

* tidy up + explain

* update to allow paging

* make admin emojis pageable

* fix mixed case paging

* normalize emoji queries a bit better

* test emoji get paging

* make limit optional

* fix incorrect path in media cleanup tests

* i have bad coder syndrome

* don't trimspace

* rename -> GetUseableEmojis

* wrap emoji query in subquery
avoid selecting more than we need

* fix a bit of sillyness teehee

* fix subquery postgres woes

internal/api/model/admin.go

@@ -80,6 +80,35 @@ type AdminReportInfo struct {
 	Statuses []Status `json:"statuses"`
 }
 
+// AdminEmoji models the admin view of a custom emoji.
+//
+// swagger:model adminEmoji
+type AdminEmoji struct {
+	Emoji
+	// The ID of the emoji.
+	// example: 01GEM7SFDZ7GZNRXFVZ3X4E4N1
+	ID string `json:"id"`
+	// True if this emoji has been disabled by an admin action.
+	// example: false
+	Disabled bool `json:"disabled"`
+	// The domain from which the emoji originated. Only defined for remote domains, otherwise key will not be set.
+	//
+	// example: example.org
+	Domain string `json:"domain,omitempty"`
+	// Time when the emoji image was last updated.
+	// example: 2022-10-05T09:21:26.419Z
+	UpdatedAt string `json:"updated_at"`
+	// The total file size taken up by the emoji in bytes, including static and animated versions.
+	// example: 69420
+	TotalFileSize int `json:"total_file_size"`
+	// The MIME content type of the emoji.
+	// example: image/png
+	ContentType string `json:"content_type"`
+	// The ActivityPub URI of the emoji.
+	// example: https://example.org/emojis/016T5Q3SQKBT337DAKVSKNXXW1
+	URI string `json:"uri"`
+}
+
 // AdminAccountActionRequest models the admin view of an account's details.
 //
 // swagger:ignore