feat(#122): add support for jr:preload

[garethbowen]

Closes #122

I have verified this PR works in these browsers (latest versions):

• Chrome
• Firefox
• Safari (macOS)
• Safari (iOS)
• Chrome for Android
• Not applicable

What else has been done to verify that this works as intended?

Testing.

Why is this the best possible solution? Were any other approaches considered?

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Introduces new functionality.

Do we need any specific form for testing your changes? If so, please attach one.

From this PR: packages/common/src/fixtures/test-javarosa/resources/preload.xml

<?xml version="1.0"?>
<h:html xmlns="http://www.w3.org/2002/xforms" xmlns:h="http://www.w3.org/1999/xhtml" xmlns:jr="http://openrosa.org/javarosa">
    <h:head>
        <h:title>jr:preload</h:title>
        <model>
            <instance>
                <data id="preload" version="1">
                    <today/>
                    <start/>
                    <end/>
                    <deviceid/>
                    <phonenumber/>
                    <email/>
                    <username/>
                    <meta>
                        <instanceID/>
                    </meta>
                </data>
            </instance>
            <bind jr:preload="date" jr:preloadParams="today" nodeset="/data/today" type="date" readonly="true()"/>
            <bind jr:preload="timestamp" jr:preloadParams="start" nodeset="/data/start" type="dateTime" readonly="true()"/>
            <bind jr:preload="timestamp" jr:preloadParams="end" nodeset="/data/end" type="dateTime" readonly="true()"/>
            <bind jr:preload="property" jr:preloadParams="deviceid" nodeset="/data/deviceid" type="string" readonly="true()"/>
            <bind jr:preload="property" jr:preloadParams="phonenumber" nodeset="/data/phonenumber" type="string" readonly="true()"/>
            <bind jr:preload="property" jr:preloadParams="email" nodeset="/data/email" type="string" readonly="true()"/>
            <bind jr:preload="property" jr:preloadParams="username" nodeset="/data/username" type="string" readonly="true()"/>
            <bind jr:preload="uid" nodeset="/data/meta/instanceID" type="string" readonly="true()"/>
        </model>
    </h:head>
    <h:body>
        <input ref="/data/today">
            <label>today</label>
        </input>
        <input ref="/data/start">
            <label>start</label>
        </input>
        <input ref="/data/end">
            <label>end</label>
        </input>
        <input ref="/data/deviceid">
            <label>deviceid</label>
        </input>
        <input ref="/data/phonenumber">
            <label>phonenumber</label>
        </input>
        <input ref="/data/email">
            <label>email</label>
        </input>
        <input ref="/data/username">
            <label>username</label>
        </input>
        <input ref="/data/meta/instanceID">
            <label>instanceID</label>
        </input>
    </h:body>
</h:html>

What's changed

When loading the form, check for bind preloads, and set the value as appropriate.
When preparing for submission, check for end binds and set the value.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9ff6c01

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@getodk/xforms-engine	Minor
@getodk/web-forms	Minor
@getodk/scenario	Minor
@getodk/common	Minor
@getodk/xpath	Patch

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[garethbowen]

This is within the margin of error but in my testing speeds up the suite by around 4%

[garethbowen]

You can now optionally pass in properties in to the vue component, specifically the users email, phone number, and username. Additionally you can pass in the deviceid - if you don't then one will be generated for you.

[garethbowen]

I needed something for the e2e testing to work with.

[garethbowen]

By default this will get generated and stored in the browser. However it won't get used unless you specify the bind in the xform. I think this is acceptable from a tracking perspective, because the part that goes to the server is opt-in.

[garethbowen]

Using listeners in this way feels slightly awkward. An alternative would be to iterate through the binds looking for revalidate actions which would be cleaner but be a performance hit. I'm open to suggestions here...