feat: add support for identifyText and identifyImage

[shimms]

Allows driver developers to specify a identifyText and identifyImage in package.json which then get used in the identify dialog in Composer.

Generates identify_text and identify_image values in driver.xml:

<config>
    <script jit="1" file="driver.lua"/>
    <documentation file="www/documentation.html"/>
    ...
    <identify_image>www/identify_image.png</identify_image>
    <identify_text>Text to display on the identity dialog.</identify_text>
    ...
</config>