Enable Clipboard shortcut for pinned entries

## Competition

This feature is supported by clipboard on Microsoft *Swiftkeyboard*.

In the following screenshot, we can see the UI for setting up clipboard shortcut in the app:


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In the following screenshot when I typed the shortcut `1h1` and the middle suggestion is the pinned clipboard entry associated with that shortcut.


## How it works

One can assign single or multiple characters as a shortcut, to a particular pinned clipboard entry.

When this shortcut is typed by the user, then the pinned shows the particular pinned entry into suggestion box and pastes the entire content.

## Purpose

This is useful as if one has several pinned statements then its hard to visually find pinned statements from clipboard.

Start by locating the clipboard feature's pinned-entry data, configuration UI, and suggestion-generation entry points in the Kotlin Android app. Trace how pinned entries are displayed and pasted, then define how shortcuts are stored and matched; done means users can assign shortcuts to pinned entries and selecting a match suggests and pastes the full entry.

Written by the indexing model from the issue text.