Previous chats lost without access to existing session

**Describe the bug**
Use case: using Element as work team chat, replacement for Slack / Mattermost / Rocket.chat.

As a user when I download the Element client I cannot access previous chats because I don't have access to pre-existing sessions. This happens repeatedly if eg I only use Element on Android and need to remove the app and reinstall it (eg for reclaiming storage space or to take a break from notifications).

Losing access to existing messages is not a viable option for professional use. As a user I dont remember if I have other sessions open on other devices, probably not.

Consider sporadic users who install the app for a conference, remove it, then reopen it 6 months later - messages should not be lost in this case either

**To Reproduce**
Steps to reproduce the behavior:
1. Install and run Element
2. Start chats with found contacts
3. Delete the app to save storage space
4. Reinstall the app later
5. Observe the inability to access old chats

**Expected behavior**
My account messages are accessible following application installation, or installation on another device, without reference to a pre-existing install and session which may or may not exist. Account recovery via Email, 2FA, or SMS would be viable.

**Smartphone (please complete the following information):**
- Device: Samsung S9
- OS: Android 9

**Additional context**
- App version and store: 1.0.14 Play store
- Home server: matrix.org