uprobe: bundle attach location+cookie via UProbeAttachPoint

[swananan]

This follows the #1417 review discussion:

By bundling location + cookie into a UProbeAttachPoint we get a more idiomatic Into<_> entry point, keep the one-to-one relationship enforced by the type system, and make it easier to extend attach with multi-location support without introducing parallel arrays or a brand new API.

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[tamird]

@tamird reviewed 15 files and all commit messages, and made 4 comments.
Reviewable status: all files reviewed, 4 unresolved discussions (waiting on @swananan).

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test/integration-test/src/tests/uprobe_cookie.rs line 29 at r1 (raw file):

    const PROG_B: &str = "uprobe_cookie_trigger_ebpf_program_b";
    let attach = |prog: &mut UProbe, fn_name, cookie| {
        prog.attach((fn_name, cookie), "/proc/self/exe", None)

would be nice to use the explicit form here (UProbeAttachPoint { .. }).

In fact, I think we should probably drop the conversion from a tuple, it doesn't buy as anything (the existing conversion traits were here to avoid source breakage relative to the previous API that took just a string)

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aya/src/programs/uprobe.rs line 53 at r1 (raw file):

/// The location in the target object file to which the uprobe is to be
/// attached.
#[derive(Debug, Clone)]

do we need these? ditto below on UProbeAttachPoint

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aya/src/programs/uprobe.rs line 98 at r1 (raw file):

        self.cookie = Some(cookie);
        self
    }

is there precedent for this builder pattern? i'd prefer to avoid it

actually, why do we need this whole impl block at all? all fields are pub

Code quote:

    /// Sets the cookie for this attach point.
    pub fn with_cookie(mut self, cookie: u64) -> Self {
        self.cookie = Some(cookie);
        self
    }

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aya/src/programs/uprobe.rs line 148 at r1 (raw file):

    /// argument may be just a location (no cookie), a [`UProbeAttachPoint`], or
    /// a `(location, cookie)` tuple; the latter two set the cookie explicitly.
    pub fn attach<'loc, T: AsRef<Path>, Point: Into<UProbeAttachPoint<'loc>>>(

plz rename 'loc

[swananan]

@tamird thanks for the review, I have addressed all the comments. I misused build pattern here, since pub fields are enough.

[tamird]

@tamird reviewed 3 files and all commit messages, made 1 comment, and resolved 4 discussions.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @swananan).