[SPARK-53573][SQL] Allow coalescing string literals everywhere

[srielau]

What changes were proposed in this pull request?

As part of generalizing the usage of parameter markers, we want to also generalize the ability to chain string literals in more places than only expressions.
This allows for fuctionality such as: spark.sql("CREATE TABLE ... LOCATION :root '/subdir'", Map("root" -> "/data")
to turn into:
CREATE TABLE ... LOCATION '/data/subdir'

String coalescing works now nearly everywhere with two cave-ats:

• typed-literals
  TIMESTAMP :param collides with json path jsonstr:path.
  I think tat's acceptable as most typed literals take strings and allow :: or CAST casting. And of course one can always pass a typed parameter marker
• property lists allow equal signs to be optional. That means we don't know where the split key and value. OPTIONS however already allowed constants which included coalescing. So precedence clarifies that, in teh absesne of an equal sign only the first string literal is the key. All subsequent literals compose the value.

Why are the changes needed?

Greatly increases the power of parameter markers without having to build heavy expressions and refactoring code

Does this PR introduce any user-facing change?

Yes, it is an additive feature

How was this patch tested?

Written a new set of tests StringLiteralCoalescingSuite

Was this patch authored or co-authored using generative AI tooling?

Claude Sonnet 4.5

[dtenedor]

Thanks for working on this, it will make the SQL syntax better!