Tamil: 3.5 Initial letter styling

[r12a]

3.5 Initial letter styling
https://w3c.github.io/iip/gap-analysis/taml-gap.html#initialletter

Comment from Muthu:

Need to be mindful of conjuncts as defined in 2.8 above.

[r12a]

I added a section on Styling initials to the requirements doc, and to the gap-analysis doc. I'd be grateful for review and comments. cc @murasu

[r12a]

Oops.
The link to the gap-analysis section is https://w3c.github.io/iip/gap-analysis/taml-gap.html#initialletter
The link for the requirements doc is https://w3c.github.io/iip/tamil/#styling-initials

[r12a]

I also created an interactive test and a test script to go with it.

[r12a]

There is also an interactive test for first-letter selection, and a test script for that too.