[3.14] gh-139742: Add support for Python 3.14 t-string prefixes in IDLE colorizer and tests (GH-139756) (#139831)

gh-139742: Add support for Python 3.14 t-string prefixes in IDLE colorizer and tests (GH-139756)

Add 't' prefix to colorizer.py stringprefix regex to support Python 3.14 template strings.
Add t prefixes to test_colorizer.py source test text and adjust line numbers on test methods.
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(cherry picked from commit 6fd141834193e3dc2423e785d97eb127c972a70e)

Co-authored-by: Anuradha Agrawal <paysur2111@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>