Editorial: Standardize preambles for Environment Record concrete methods

Reword existing preambles and fill in missing ones
according to the format set out in issue tc39#1981.

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HasThisBinding() + HasSuperBinding():
- When the algorithm is simply returning a specific Boolean value,
  create a Note after the algorithm re providing (or not) the binding
  (moving the sentence from preamble if applicable).
- Reword re use of the word "regular" (avoid it or explain it).

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Present never-invoked concrete methods more consistently.

Specifically, present DeleteBinding for module ER
more like CreateImmutableBinding for object ER.

- Don't say it "refuses to delete bindings",
  because that sounds like it throws an error if invoked,
  when in fact it's never invoked.

- Drop the emu-alg that just asserts it's never invoked.