Change TEXTING_REQUEST_CODE to fit 16-bit limit

[barreeeiroo]

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For all other changes:

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What does this PR accomplish?

Description

Updated the texting request code to fit within Android's 16-bit limit, changing it from 'TEXT' to 'TX'.

Fixes https://community.kodular.io/t/while-using-texting-component-runtime-error-can-only-use-lower-16-bits-for-request-code/145085?u=diego

Resolves # .

[barreeeiroo]

I think this bug may have been introduced back in 2017, when Form changed from Activity (not enforcing this limit) to AppCompatActivity: 6e23c47#diff-52eaaa99b3c97da14d0b9da6a80d9e8a3cca42153e5bc9976dbc731460c8ca41R106

Refs:

• https://stackoverflow.com/a/33331459/6626193
• https://stackoverflow.com/a/38221069/6626193

[barreeeiroo]

Note that there's probably another bug with how we generate requestCode's as a whole: https://github.com/mit-cml/appinventor-sources/blob/master/appinventor/components/src/com/google/appinventor/components/runtime/Form.java#L734

We just increment this, so if we run out of ints in the 16 bit space, we will start throwing exceptions... It's unlikely this to happen, but possible.

[ewpatton]

LGTM