API changes to make FLEDGE understand ad sizes (#417)

* Update generateBid()

* Most of joinAdInterestGroup changes

* Expand description of joinAdInterestGroup fields

* Add runAdAuction requestedSize field

* Update generateBid description

* Update FLEDGE.md

* Update FLEDGE.md

* Update k-anon check

* Update FLEDGE.md

* Describe size macros

* Update Release_Notes.md

* Fix typo

* Describe how size returned from generateBid is used

* Remove mention of filtering

* Describe purpose of sizes in interest group declaration

* Update Release_Notes.md

* Update Release_Notes.md

* Update Release_Notes.md

* Accept `sizeGroups` suggestion

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion to use group1 and group2 in ad size example

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion to explicitly call out the "size3" example size->sizeGroup implicit coercion

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion to call out AD_WIDTH and AD_HEIGHT explicitly in "see above"

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion to turn "url+size" into "URL and size"

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Accept suggestion to rephrase interest group size declaration description

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Mention optionality of interest group size fields

* Remark that sizes are also optional in generateBid

* Add more (optionally)s

* Update Release_Notes.md

* Add more optionality

* Add more optionality

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Update FLEDGE.md

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Update FLEDGE.md

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Update Release_Notes.md

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Update requestedSize description

* Update browser signals

* Update FLEDGE.md

* Change M115 to M116 for browser signals additions

* Fix "bid" -> "auction config"

* Remove renderSize from reportResult signals

* Update FLEDGE.md

* Update FLEDGE.md

* Update FLEDGE.md

Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>

* Fix rebase issue

* Add extra macro format

* Fix {size: ...}

* Add explicit transition period

* Add explicit transition period

* Add explicit transition period

* Update FLEDGE.md

Co-authored-by: Alonso Velasquez <114112643+ajvelasquezgoog@users.noreply.github.com>

* Fix link and perens.

* Update FLEDGE.md

Co-authored-by: Alonso Velasquez <114112643+ajvelasquezgoog@users.noreply.github.com>

* add missing space

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Co-authored-by: Paul Jensen <JensenPaul@users.noreply.github.com>
Co-authored-by: Alonso Velasquez <114112643+ajvelasquezgoog@users.noreply.github.com>