Emacs Command to Delete Up to Non-Whitespace Character

You might try delete-indentation, my favorite command for joining multiple lines into one line. In your example, put the cursor on the line with "second" and hit M-^ twice. Here are the docs:

M-^ runs the command delete-indentation, which is an interactive compiled Lisp function in simple.el.

It is bound to M-^.

(delete-indentation &optional arg)

Join this line to previous and fix up whitespace at join. If there is a fill prefix, delete it from the beginning of this line. With argument, join this line to following line.

Take a look at the fixup-whitespace function. It comes with Emacs, in simple.el. Its docs are:

Fixup white space between objects around point. Leave one space or none, according to the context.

A similar function, just-one-space, that

Deletes all spaces and tabs around point, leaving one space

is typically bound to M-SPC.

Specifically, is there a command that will delete all whitespace from the point to the first non-whitespace character?

There's a command that does almost that:

M-\ runs the command delete-horizontal-space which is an interactive compiled Lisp function in `simple.el'.

It is bound to M-\.

(delete-horizontal-space &optional backward-only)

Delete all spaces and tabs around point. If backward-only is non-nil, only delete them before point.