Handle static text messages in TextLogView gracefully, handle overrides

[Wumpf]

What

First commit wires the TextLogView to the override system. Making this part of:

• Not all items in override UI always apply to visualizers #6595

Second commit makes us handle static text without errors. Allowing non-catastrophic behavior when changing the text message:

Text run using:

import rerun as rr

rr.init("rerun_example_text_log", spawn=True)

rr.set_time_seconds("t", 0.0)
rr.log("log", rr.TextLog("Application started.", level=rr.TextLogLevel.INFO))
rr.set_time_seconds("t", 0.1)
rr.log("log", rr.TextLog("Application wumpfed.", level=rr.TextLogLevel.WARN))
rr.set_time_seconds("t", 100.0)
rr.log("log", rr.TextLog("Thing happening", color=0xFF9001FF, level=rr.TextLogLevel.ERROR))

text.editing.mp4

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
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