Feature request: KeepassDX as a share target for Termux-share

**Is your feature request related to a problem? Please describe.**
I'd like to be able share various keys/text (ssh, gpg, etc) from Termux to KeePassDX and create entries without using the Android clipboard due to any app being able to listen for clipboard changes.

**Describe the solution you'd like**
On the Termux side of things we have the `termux-share` command which can
> "Share a file specified as argument or the text received on stdin if no file argument is given."

This means I can share a path to a keyfile such as id_rsa or the actual contents via pipes: `cat ~/.ssh/id_rsa.pub | termux-share`

The full usage of `termux-share`:

`$ termux-share -h`
`Usage: termux-share [-a action] [-c content-type] [-d] [-t title] [file]`
`Share a file specified as argument or the text received on stdin if no file argument is given.`
` -a action which action to performed on the shared content: edit/send/view (default:view)`
` -c content-type content-type to use (default: guessed from file extension, text/plain for stdin)`
` -d share to the default receiver if one is selected
instead of showing a chooser`
` -t title title to use for shared content (default: shared file name)`

I can provide sample intents that are created with `termux-share` if needed.
**Describe alternatives you've considered**
related to #280 though I couldn't find any application-generic issue about KeePassDX being a share reciever to create entries

**Additional context**

Start by reviewing how Termux-share sends files and text to Android share targets, using the termux-share usage and sample intents mentioned in the issue. Determine how KeePassDX should receive those inputs and create entries without the clipboard. Done means KeePassDX is offered as a share target and can create entries from shared key files or text.

Written by the indexing model from the issue text.