RFR: 8339800: Prefer invokeBasic in BootstrapMethodInvokers

[Claes Redestad]

Switching to `invokeBasic` for type-check invokes in `BootstrapMethodInvokers` instead of `invokeExact` avoids some `MethodHandleNatives.linkMethod` calls during bootstrap. This brings a tiny but measurable once-per-bootstrap method win. Both before and after we lean on the static casts in BootstrapMethodInvokers to sanitize against type mismatches.

-------------

Commit messages:
 - Prefer invokeBasic in BootstrapMethodInvokers

Changes: https://git.openjdk.org/jdk/pull/20926/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20926&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339800
  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/20926.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20926/head:pull/20926

PR: https://git.openjdk.org/jdk/pull/20926