[Parley Draw]: Add Vello Copy

[taj-p]

Copying Vello's Text Logic to Parley Draw

To kick off implementation of Parley Draw, we're firstly copying over the Vello implementation.

EVERYTHING WILL CHANGE SIGNIFICANTLY (especially APIs!). For now, we're simply copying the code across for the purposes of using it as a foundation to build off and to allow us to start exploring hint aware shaping.

This approach has been OK'd by @dfrg .

Changes made to the copy

• Added a vello_cpu_render example that uses Parley Draw so that we can keep track of how the API evolves. After we're happy with Parley Draw, I recommend applying it to our other examples.
• Feature gated vello_cpu's implementation of GlyphRender and ColrRender so that consumers aren't required to use it. However, we still depend on vello_common.
• We have to pain to Vello's github repository because Pixmap hasn't yet been moved from vello_cpu to vello_common in the latest 0.0.4 release.
• We pass the GlyphCaches into GlyphRunBuilder instead of having the trait own them. This reflects how we will eventually support sharing the hinting instance cache between the shaper and renderer. But, of course, this is all subject to change.
• Updated MSRV to 1.88 to use Vello (which has an MSRV of 1.88).

Immediate Follow Ups

• I decided not to port the tests over at the same time. I suspect we might want to discuss the best way to execute tests for Parley Draw, so I think that's best discussed in a follow up after this is merged. Right now, I'm thinking of moving the existing parley tests out to parley_tests and using Parley Draw for rasterising those tests (alongside additional draw only tests like COLR emoji rasterisation tests).

Example

This is the output of the new example:

Reviews

Since most of this code has already been reviewed in Vello, I suggest we focus the review on the changes listed above.

[nicoburns]

This seems reasonable as initial version.

However, I think we should eliminate the dependency on vello_common (except when using vello_cpu) sooner rather than later. Looks like it's just being used for the Pixmap type which is mainly being used for png decoding? IMO that doesn't justify the dependency.

[xStrom]

Vello copyright acknowledgement must remain.