Deleted descriptions of and references to legacy wallets

[TinaKT]

Purpose

The purpose of the pull request is to delete all descriptions of and references to legacy wallets.

Changes

Updated the following pages:

• Send CCD
• Find and share your account address
• Connect dApps to wallets
• Tokens in the wallet
• Unshield CCD on an account
• Scheduled releases
• Inspect a release schedule
• Export a private key
• Add a validator
• Change validator options
• Delegate to a staking pool or passive delegation
• Remove delegation to a staking pool or passive delegation
• Update delegation to a staking pool or passive delegation

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.

By submitting the contribution I accept the terms and conditions of the
Contributor License Agreement v1.0

• link: https://developers.concordium.com/CLAs/Contributor-License-Agreement-v1.0.pdf

[dragosgd]

LGTM