feat: configurable alias prefix

[petersalomonsen]

Configurable Alias is about having the option to not only use the alias_ when referencing common constants in your code. This can be references to a near account, an external URL or whatever you need to reference in your code.

In the updated documentation you can read about the new aliasPrefix and aliasesContainsPrefix settings, which gives you the option to use another prefix than alias and also that your aliases file contains the prefix itself in the names of the object keys.

Here's from the "Custom alias prefix" section of the documentation:

If your aliases are prefixed with another keyword than alias, you may configure this using the aliasPrefix property. You may also include the prefix in the keys of your alias json file. Here is an example:

 {
   "account": "[MAINNET_ACCOUNT_ID]",
   "aliases": ["./aliases.mainnet.json"],
   "aliasPrefix": "REPL",
   "aliasesContainsPrefix": true,
 }

and then with your aliases.mainnet.json like this:

{
  "REPL_NAME": "world"
}

If your widget file looks like this:

export default <h1>Hello ${REPL_NAME}!</h1>;

Then the alias will be replaced like this:

export default <h1>Hello world!</h1>;

This update also makes it more compatible with bos-loader so that you can more easily use existing project with replacement configurations with bos-workspaces.

fixes #109