Automated with clang-tidy -fix -checks=-*,modernize-use-default-member-init

- Also eliminate unneeded std::string() around some literal strings.

- Use range for loops for processor models and schedule classes.
- Cleanup duplicated or unused iterators in CodeGenSchedule.h

- Use range for loops and `enumerate` in a few places.
- Use `StringRef` for `TargetName` in `InstrInfoEmitter::run`.
- Use `\n` character for new line instead of string.
- Use StringRef in `InstrNames` (instead of std::string) and 
  avoid string copies.

Use this to remove a linear scan from CodeGenProcModel::hasReadOfWrite.

This reduces build time of RISCVGenSubtargetInfo.inc on by machine from
~6 seconds to ~3 seconds.

2 of the 3 callers of each of these already had a reference they
converted to index. Use that reference and make the one caller
that only has an index responsible for looking up the reference from it.

Use this to improve performance of SubtargetEmitter::findWriteResources
and SubtargetEmitter::findReadAdvance. Now we can do a map lookup
instead of a linear search through all WriteRes/ReadAdvance records.
    
This reduces the build time of RISCVGenSubtargetInfo.inc on my
machine from 43 seconds to 10 seconds.

It's better to cast away constness on the reference being returned than
to cast away constness on the this pointer.

The function called find_if and converted the iterator to an index.
The caller then had to check the index being non-zero to know if the
find succeeded.

Seems better to just do the find and distance in the caller.